The standard is ElTorito. I don't know where or if you can find a copy of it for free. It's probably over your head anyway. (That's not intended as a dig; I'm sure it's over mine, too.) Generally, though, the way it works is to emulate a bootable floppy or hard drive. In fact, IIRC, if that boots into DOS, you'll se it as drive A:. I do know that you can use 2.88MB images, if 1.44MB isn't enough, and I'm 98% positive that you can use arbitrarily sized images as well.

I never do this sort of thing under DOS/Windows. I use a program under Unix called mkisofs that deals with all of this sort of thing for me. It's possible that someone has ported it to DOS/Windows, as all it really does is create the ISO9660 image. You then have to burn it with a different program. Most Windows burners will do this without a hitch.