Whatever your reasons are for doing it, booting your Mac from another disk is never an easy task. Thankfully, programs like QuickBoot are around to make life a bit easier for you.
Not only does the application allow you to boot from a different drive, but you also get some interesting options, such as the ability to restart your system from a partition or an external device.
One of the good things about this is that after resumption with QuickBoot, the system will reboot from the default drive next time you use it.
Although the program makes it easier to boot from another disk (such as Windows, for instance), you still need to take care with it as incorrect use can lead to problems with your Mac.