Again I was unable to find out how to do this with the documentation on this website but was eventually able to stumble across the solution.
1. Extract the ubcd files from the iso
2. Copy all the files from i386 off your xp setup cd into the root of the ubcd (ie /ubcd/i386)
(If you just want a bootable recovery console I downloaded one some time ago as an iso with just the files required to run it, it is less than 10mb total. Unfortunately I have no idea now where i got it then.)
3. Get Bart's Bart's wxp10.zip:
http://www.nu2.nu/download.php?sFile=wxp10.zip
4. From wxp10.zip copy w2ksect.bin win51 and win51ip to the root of ubcd
5. Go into i386 and delete bootfix.bin (unless you want to hit any key to boot from cd)
6. If for some reason you want more than one xp version on a disc rename i386 and then take a hex editor and replace any occurance of i386 in /w2ksect.bin and /i386/SETUPLDR.BIN with whatever you are naming your folder (probably a good idea to keep it short) this works fine with the recovery console only but i have no idea what additional settings would be required for a full xp install
7. In /custom/custom.cfg add the entry for winxp recovery console
LABEL recovery
MENU LABEL XP Recovery Console
KERNEL /w2ksect.bin
APPEND
Job done.