I'm making a drum cake that is going to be a black forest cake, for that reason I don't want to cover it with mmf since I don't think the flavors will mix well.  My plan was to use chocolate ganache and somehow paint it to give it a wood color.  Is this even possible? I've never used ganache before.

I doubt that will work well. I'd go ahead and cover it with a very thin layer of fondant to give yourself a base to paint on. Or maybe you could use modeling chocolate, at least that would go better with the flavors.

Ok thanks, I was just checking.  I've decided to do a chocolate ganache and a thin layer of chocolate fondant on top to paint. I experimented with marbling the chocolate fondant to get the wood effect I'm looking for but I didn't like it.