The only problem with that is that enemies will automatically target your hero even if he is hidden. Your best best is triggering his getting replace with a unit who looks like a doodad and would have all the destinguishable features of one, except be a controllable unit. Then the heores could target your unit but they'd have to attack it to reveal your guy. There's also a preset setting which hides a unit from the map (it's in the units settings). What could be neet is if you're hero when completely seethrough, etheral, and was undetecable on the map, and seen as as passive so no enemy computer would detect you. This would be the greatest camoflage ability ever. But that's just an idea i don't quite know how to do.
Hope the first suggestion, however, helps.
