Wondering if theres a way to take a 2d unit and have it appear in the game somehow.

I would say, that once you actually play civ4 you wouldn't want to do that. :) but that's just my 2 cents

Hm, it would look very flat. Like seeing a cardboard cut-out of a person in a picture with real people in it.

Well I just thought it would be nice to put Civ3's vast libraury to work in Civ4, even if it doesn't like quite right lol. Plus I make units for civ3 and for the moment I can't make any for 4.