My friend wants to run a kba100 celestion combo sub/amp that's normally for home use on his car, by means of an inverter... is this possible?

 

yes but it is ghetto, besides a home audio sub is made to interact with the acoustics of a large room not a small trunk, so it might not sound too good.
One of my dumb *** friends in high school did that and it was weak and distorted.
telll him to just spend the money and buy car audio. if he runs the amp through the thin wire in a power inverter he is going to starve it anyway.