Quote: "you'll need to either cut the terrain up in small portions manually and place them all correctly afterwards"
I will insert it as an entity, not a segment.
Quote: "to keep manually editing the terrain's vertices until your AI won't fall through it anymore, or get stuck"
I just place it a little bit above the terrain, and then it just lands on top of the terrain.
Quote: "as for CS4, it won't work for terrains that well.. It's mostly for building interiors for as far as I've seen of it so far."
Rats, that is what I use all of my other programs for.
Thanks though, atleast you are helping.