Come on guys. This was like the *first* web page for seriously hacking the Mac hardware: http://homepage.mac.com/schrier/mhz.html
It's been around, though at a different URL, since the early/mid 90s.
Marc Schrier was one of the principals of Output Enablers. They sold clock chipping kits for pretty much every machine that could be clock chipped. They had a nice clip-on that fit over metal can oscillators, disabled them and substituted another oscillator's signal and a different plastic socket which slid over surface mount oscillators and provided the same function.