Originally Posted by jawathehutt
Im pretty sure theres a few things laying around on filefront somewhere that let you do that without disrupting multiplayer, just download one of them.
No, the code required for that would break multiplayer, guaranteed (because it would require the map's script to be substantially different). The only thing available for download that enables AI heroes is the "AI Hero Support" mod (a worthwhile download, to be sure), which doesn't do anything to the original maps, but rather, adds a mappack of the original maps (duplicated) on which you can play with AI heroes.
There's absolutely no way - to reiterate - of having AI heroes in singleplayer on the exact same maps as you want to work with everyone else in multiplayer.