This guide explains how to change the WB scenario.
Open the worldbuilder file in notepad, in My documents/my games/beyond the sword/saves/worldbuilder.
After the BeginTeam/EndTeam, you should see something like this(the leadertype, civdesc, etc. will change dependent on the leader). This example has louis.:
BeginPlayer
Team=0
LeaderType=LEADER_LOUIS_XIV
LeaderName=Mad Scientist
CivDesc=TXT_KEY_CIV_FRANCE_DESC
CivShortDesc=TXT_KEY_CIV_FRANCE_SHORT_DESC
CivAdjective=TXT_KEY_CIV_FRANCE_ADJECTIVE
FlagDecal=Art/Interface/TeamColor/FlagDECAL_FleurDeLis.dds
WhiteFlag=0
CivType=CIVILIZATION_FRANCE
Color=PLAYERCOLOR_DARK_BLUE
ArtStyle=ARTSTYLE_EUROPEAN
PlayableCiv=1
MinorNationStatus=0
StartingGold=0
StartingX=53, StartingY=38
StateReligion=
StartingEra=ERA_ANCIENT
RandomStartLocation=false
CivicOption=CIVICOPTION_GOVERNMENT, Civic=CIVIC_DESPOTISM
CivicOption=CIVICOPTION_LEGAL, Civic=CIVIC_BARBARISM
CivicOption=CIVICOPTION_LABOR, Civic=CIVIC_TRIBALISM
CivicOption=CIVICOPTION_ECONOMY, Civic=CIVIC_DECENTRALIZATION
CivicOption=CIVICOPTION_RELIGION, Civic=CIVIC_PAGANISM
Handicap=HANDICAP_MONARCH
EndPlayer
This should be the start file, values may vary depending on the handicap, starting values, etc.
To change the leader from Louis to Sury, make the highlighted changes.
BeginPlayer
Team=0
LeaderType=LEADER_
SURYAVARMAN
LeaderName=Mad Scientist
CivDesc=TXT_KEY_CIV_
KHMER_DESC
CivShortDesc=TXT_KEY_CIV_
KHMER_SHORT_DESC
CivAdjective=TXT_KEY_CIV_
KHMER_ADJECTIVE
FlagDecal=Art/Interface/TeamColor/FlagDECAL_
Khmer.dds
WhiteFlag=0
CivType=CIVILIZATION_
KHMER
Color=PLAYERCOLOR_
MIDDLE_BLUE
ArtStyle=ARTSTYLE_
ASIAN
PlayableCiv=1
MinorNationStatus=0
StartingGold=0
StartingX=53, StartingY=38
StateReligion=
StartingEra=ERA_ANCIENT
RandomStartLocation=false
CivicOption=CIVICOPTION_GOVERNMENT, Civic=CIVIC_DESPOTISM
CivicOption=CIVICOPTION_LEGAL, Civic=CIVIC_BARBARISM
CivicOption=CIVICOPTION_LABOR, Civic=CIVIC_TRIBALISM
CivicOption=CIVICOPTION_ECONOMY, Civic=CIVIC_DECENTRALIZATION
CivicOption=CIVICOPTION_RELIGION, Civic=CIVIC_PAGANISM
Handicap=HANDICAP_MONARCH
EndPlayer
Obviously, depending on the leader, the changed things will vary. For example, if changing to lincoln, you will change the ARTSTYLE to something different than Asian.