Oh, Should have added that if you setup your BIOS to boot from a floppy first (which is normal setup), CD, even USB memory sticks, then it will treat them in exactly the same way as a HD, i.e. look for the very first piece of information stored on the device and take it from there.

This is an easy way to test things, as you leave your HD alone, and put the new code on your floppy or whatever, and see what happens when you boot from it ..
Plenty of utilities on the net which you can find via google which will let you setup a floppy to do this.