Can I use white chocolate ganache in cake pops, instead of frosting, to hold the cake together. Vanilla frosting is just too sweet.

I don't see any reason why you couldn't. Ganache is just a type of frosting in many ways. The point is just to stick all the cake crumbs together, so that you can mold them. You could probably even warm up any left over ganache to dip them in as well.