I know Jack (pbkid) put some sliders on his VX and I remember him telling me that he had to use a 90 degree drill to get into some of the tight spaces under there. Patience, and a good drill bit, will go a long way.
On a similar note: I had heard that we are NOT supposed to weld to our frames. Something about the heat de-stablizing the metal structure and possibly causing failure. Can anyone confirm/deny my fourth hand information?
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong, it usually turns out to be impossible to get at or repair."
-Douglas Adams, Mostly Harmless