Right, I think that this should work - 364 turns, divided into the years 333 - 292. The early turns will represent less time than the late turns (1 week per turn at the beginning, 16 weeks per turn at the end). I recon that with the timings I'm looking at then Alex should potentially die by around the 200th turn, at the earliest. This should be approximately when he returns back in Persia after the first Indian campaign.
There will be five tech trees:
The Timer techs are researched by Cathay, Axum, Nubia, Numidia, Dacia, Thrace, and western / northern barbarian civs. They'll just be named after years (like in RFRE) and will allow some (limited) units and buildings. All civs will be able to acquire these techs through trade / great library. They will take 26 turns to research (maximum research time). This line will end with the possibility of a single city cultural victory, if the player makes it that far.
The Persian techs can only be researched by Persia, Bactria, Sogdiana, Arabia and Scythia. This line will allow plenty of powerful persian units to be built at appropriate times, intended to keep the early part of the game a challenge for Alex. This line will start from the Persian Heritage era-none tech.
The Indian techs can only be researched by Taxila, Paurava and Maurya. It will act in a similar way to the Persian line, but the early parts of the tree (i.e. the part before Alex shows up) will be fairly empty. The later part will allow all sorts of nasty stuff for Chandragupta Maurya to use against Alex. This line will start from the Indian Heritage era-none tech.
The Mediteranean line will be available to the League of Corinth, Lacedaemonia, Epirus, Creta, Cyrenacia, Eastern / Western Greece, Roma, Tyrhenia, Egypt, Phoenicia, Carthage, Macedonia and Alexandria. It will allow for general development of the story in the med region, with Carthage being encouraged to build up its fleet and Roma being encouraged to build its army, Sparta being encouraged to attack Macedonia etc. This line will start from an era-none tech given to the med civs and Alex.
The Alexandrian line will basically be what I already had, a list of the conquests of Alexander. This line will lead towards the Alexandrian Empire and Burial of Alexander victory possibilities, so the player should research this line rather than the med line. This line will follow from an era-none tech only given to Alex.
Possible problems as I see it 1 - encouraging the med, persian and indian civs to research their own tech lines rather than the timer line. 2 - encouraging the Alexandrian player to research the Alexandrian line. Number 2 should be easily solved by putting some good units along that line and leaving the med line fairly sparse for Alex. The player will have a great library type wonder to keep them up to date with the rest of the mediteranean and the timers anyway.
Wow, long post without a smily.

Any possible problems people can see?