Hello all! I have a cool idea for a colonization mod but I have no time to learn how to mod civ4 since i have a work in progress civ3 mod. So im posting my idea here in case one or more experienced civ4 mod developers decide to pick it up 
Its a fictional scenario, loosely based on a number of medieval myths, especially one I saw on wikipedia about the mythical island Antilia:
So the idea is having an early iberian colonization of an american island, not necessarily a fictional island. Read Iberian, not Spanish or Porguese since they didnt exist at the time, Porto belonged to the kingdom of Leon at the time.
Some other european civs can be present, im thinking of the Leonese settling in Florida which corresponds to the description of being about the size of portugual, though not an island, the Vikings in Newfoundland or Nova Scotia, and perhaps a few pre-placed lost Greek and Phoenician colonies since there are also beliefs that some early american cultures had contact with explorers from the east, maybe even a chinese expedition in the west coast.
Some changes must be made to the indians, the Inca should be replaced by the Huari and Tiwanaku, the Aztecs by the Maya and Teotihuacan, the Anasazi and Haida should be added or replace some others, stuff to be researched.
Get rid of the founding fathers system and bring back a technology tree or something very similar.
The date is around 800aC, so there are no muskets yet, which means the europeans will not have a big military advantage over the natives. Tools should be replaced with Forged Metal, the resource required to make pre gunpowder military units and the more advanced buildings. Timber could also be used to make weapons, so there should be a greater number of military units: Archers and Spearmen (requiring a stock of timber), Armored Pikeman and Swordsmen/Axemen (depending on culture, requiring a stock of forged metal), Arquebusiers and the later gunpowder units (requiring muskets once they become available). Catapults with timber and Cannons with forged metal, each with a required building. Ships should also need a stock of timber, and forged metal for the ones armed with cannons.
Some of the indians should be promoted to full civ status, the meso american and andean ones.
No European contact for a long time, since the colonists are supposed to be running away from invasions or in search of a better life, they dont want to come back, the expedition ship is scraped to use its timber to build the town hall and the only ships able to be built until later in the game are galleys and war galleys (galeasses), uncapable of crossing the vast ocean.
An interesting scenario would be contact with the european civs at the apropriate dates, when Columbus reaches america, followed by the other navigators from the other nations. Then the player has a choice, start paying taxes in exchange for access to the european port to sell and buy goods and colonists, and money in exchange of technologies and other things. One of the european powers could for instances offer money and access to its port in exchange for an alliance against the colonies of another power. And there would be no declaration of independance, instead there will come a time when one of the powers declares war and a similar war will have to be fought, win it and all the european powers will recognise the lost colony as a new nation.
Since there's no european contact until later in the game, there will be no imigration, so the game will start with a few more colonists, there will be population increase and converted natives, and free colonists will be upgraded to masters of their profession after a while, like in col 1. Slavery could also be implemented.
If anyone picks this up I'll help with further brain storming

Its a fictional scenario, loosely based on a number of medieval myths, especially one I saw on wikipedia about the mythical island Antilia:
Antillia (or Antilia) is a mythical island which was reputed during the age of exploration to lie in the Atlantic Ocean far to the west of Portugal and Spain. The so-called Phantom Island went by various other names such as Isle of Seven Cities, Ilha das Sete Cidades (Portuguese), Septe Cidades, Sanbrandan (or St Brendan). Antillia was also connected at times with ancient legends including the Isles of the Blest and the Fortunate Islands.
A Portuguese legend tells how the island was settled in the early eighth century in the face of the Moorish conquest of Iberia by the Archbishop of Porto, six other bishops and their parishioners, seeking to avoid the ensuing Dark Age. Each congregation reputedly founded a city, which were known as Aira, Anhuib, Ansalli, Ansesseli, Ansodi, Ansolli and Con,[4] and once established burnt their caravell ships as a symbol of their autonomy. It should be noted that since said events predated the Kingdom of Portugal and the clergy's heritage marked a claim to significant strategical gains, Spain counter claimed that the expedition was, in fact, theirs.
So the idea is having an early iberian colonization of an american island, not necessarily a fictional island. Read Iberian, not Spanish or Porguese since they didnt exist at the time, Porto belonged to the kingdom of Leon at the time.
Some other european civs can be present, im thinking of the Leonese settling in Florida which corresponds to the description of being about the size of portugual, though not an island, the Vikings in Newfoundland or Nova Scotia, and perhaps a few pre-placed lost Greek and Phoenician colonies since there are also beliefs that some early american cultures had contact with explorers from the east, maybe even a chinese expedition in the west coast.
Some changes must be made to the indians, the Inca should be replaced by the Huari and Tiwanaku, the Aztecs by the Maya and Teotihuacan, the Anasazi and Haida should be added or replace some others, stuff to be researched.
Get rid of the founding fathers system and bring back a technology tree or something very similar.
The date is around 800aC, so there are no muskets yet, which means the europeans will not have a big military advantage over the natives. Tools should be replaced with Forged Metal, the resource required to make pre gunpowder military units and the more advanced buildings. Timber could also be used to make weapons, so there should be a greater number of military units: Archers and Spearmen (requiring a stock of timber), Armored Pikeman and Swordsmen/Axemen (depending on culture, requiring a stock of forged metal), Arquebusiers and the later gunpowder units (requiring muskets once they become available). Catapults with timber and Cannons with forged metal, each with a required building. Ships should also need a stock of timber, and forged metal for the ones armed with cannons.
Some of the indians should be promoted to full civ status, the meso american and andean ones.
No European contact for a long time, since the colonists are supposed to be running away from invasions or in search of a better life, they dont want to come back, the expedition ship is scraped to use its timber to build the town hall and the only ships able to be built until later in the game are galleys and war galleys (galeasses), uncapable of crossing the vast ocean.
An interesting scenario would be contact with the european civs at the apropriate dates, when Columbus reaches america, followed by the other navigators from the other nations. Then the player has a choice, start paying taxes in exchange for access to the european port to sell and buy goods and colonists, and money in exchange of technologies and other things. One of the european powers could for instances offer money and access to its port in exchange for an alliance against the colonies of another power. And there would be no declaration of independance, instead there will come a time when one of the powers declares war and a similar war will have to be fought, win it and all the european powers will recognise the lost colony as a new nation.
Since there's no european contact until later in the game, there will be no imigration, so the game will start with a few more colonists, there will be population increase and converted natives, and free colonists will be upgraded to masters of their profession after a while, like in col 1. Slavery could also be implemented.
If anyone picks this up I'll help with further brain storming