XTIDE Universal BIOS on IBM PC?

I saw that the newest versions of the XTIDE Universal BIOS have a way to use the serial port as a disk drive by connecting to another computer running XP. Since my IBM PC doesn't currently have any kind of mass storage, this seemed like it could be handy, even if it might be terribly slow. I don't have an XTIDE card, but I do have a 3com Etherlink II 3c503 that has an empty socket. I burned the 12k xtl ROM to a 27c128 and filled the extra space with zeroes. I put it in the socket and now when the computer boots up I get "DC00 ROM" on the screen just before it tries to boot from a floppy. However that's it. I tried holding down the Alt key to get it to give me a menu or scan the serial ports, but nothing happens. Is there some trick to making the XTIDE ROM work in the 3c503 socket? -- Follow me on twitter: @FozzTexx Check out my blog: http://insentricity.com