[Wlug] Xmon / Serial cable

Folks, I'd like to try my hand at debugging the kernel boot process on a Macintosh PPC. I have a couple of silly questions, though. 1) Can I debug a Mac from an x86 box using Xmon? 2) I need a null modem cable to connect my Athlon and my Mac. Any thoughts as to where I could buy such a beast, or how to wire one up from parts obtained from Radio Shack? Thanks, Skip