[Killaruna]

Yep, hello :-) Don't know if this is the right place to say it, but IMHO the interface to the bot should be on a much higher level, that makes it much easier to identify the needed functions, data, etc. That means e.g. no assumptions about engine hooks, since for the bot AI, it doesn't matter how it gets its information from the game. Again as an example the PIA framework: It has its base classes that offer most of the information a bot AI might need and it has access to engine entities via the Perceipt class. Just given this minimal framework, you could write tons of sophisticated, portable bot AIs. For PIA, a game driver would be a collection of subclasses for a specific game, plus the link to the actual game itself, which would probably look similar to something like the HPB template for HL.
This approach does not use gamedriver DLLs, i.e. you have to compile the bot for each game you want to support (which shouldn't be a big problem since you have still got the source portability). But it's so much easier to define what you need and to start working on something!