Usually those types of algorithms pull data directly from the bsp, which modders don't have access to much of the time. There are bsp tools for HL and probably quake, but given that ET:QW is heavily terrain based, and AAS sucks on terrain, you would need some method to handle terrain better.
I'm working on a navigation mesh that gets built without bsp access, which I can't rely on since my bot is cross engine/mod, and I want to better support terrain. I don't get to spend a ton of time on it since I'm also working on FF bots, but if u want to read a bit about it visit here:
http://www.omni-bot.de/e107/e107_plu...topic.php?4142
AI Wisdom and Game Gems books talk extensively about nav meshes, which is essentially what AAS is.