Unit Partial Invisibility?

How would I make a unit partially invisible? (such as DotA's phantom assassin's evasion)

give it a ghost or a permanent invisibility option
or if you just want it to look transparent use
Unit - Set Unit Vertex Color to 100, 100, 100, and 50% transparency
the less the transparency the more invisible it will be
100% is non-transparent.

Woohoo! Thanks so much!