Depending on your hardware there could be a standard process, but it almost always requires a bit of command line work, clicking cancel at the right time, and withstanding the temptation of clicking reboot when the installer asks you to.
That said, I've used OSX on non-Apple hardware for two years as my main development/entertainment machine. Upgrading wasn't desireable anyway because newer versions of OSX stopped supporting multi-monitors after 10.6.7 I believe. It really was great to be able to use OSX on my desktop.
Finally when staying on 10.6.7 really started to give problems, I decided to try Ubuntu again. I was pleasantly surprised that Ubuntu now actually is very usable as a workstation for development. It's got all window manager features 10.6.7 had, good terminal emulators, editors, and the important browsers, what more do you need? (don't say photoshop :@)