Need help installing XP on a Par M5012-01

[brucem3]

I'm trying to help someone who has an old TacoBell terminal (Par M5012-01, capacitive touch, 566MHz celeron, 256M RAM (soon 512M RAM), 20G HD) that was running custom software on top of DOS. I'm not able to find a way to install XP on it. I can get some Linux distributions to boot from a USB stick, and even get XP Recovery Console to load from a USB stick via WinToFlash. But I can't seem to get it to start XP setup from a WinToFlash USB stick, or from an external USB CD drive. The BIOS supports booting from an ATAPI CD drive but I'm thinking I'll have to get an IDE CD drive inline with the existing HD to get it to boot via CD. Anyway, would appreciate any info or tricks to get XP installed on an M5012. TIA!