Actually, I did check this out! The ones in the factory are held in place by L-brackets top and bottom, which doesn't look very elegant for home use but looks fine in the factory. However, you can drill pretty much anywhere into the M80s, since the crossovers are mounted to the input buckets. You won't hit anything and damage it. It's important to drill a pre-hole in case you run into a brace or a joint. If you drill a hole you have to put a screw in, whether you use it or not, since you don't want any air holes. Other than that, sky's the limit!
