Press F2 to enter bios settings
You need to change OS to [start] - and remember to change back to [finished] later on - this enables USB2.
Go to advanced tab in bios settings, >IDE configuration, > siliconmotion sm223ac, press [enter] – brings up a list – choose not installed. Exit and save.
Attach your ext HDD and use an ext CD/DVD-ROM drive as well. You need to add the modified files detailed in your link above to your windows XP disk (use Ultraiso or similiar to add and then burn a disk) - these allow the USB to be detected first (I think). Be METICULOUS in following the instructions - errors here will give boot errors later and it will be a no go. EMail me and I'll mail you the modded files I made.
Turn on your eee and press ESC to enter boot options - select your CDROM and away you go.
It takes quite a while for XP to load. When XP is running you also need to go to administrative tools, management, storage, and remove the drive letter for the BIOS partition.
That should be it.
Hope that helps - I found it quite frustrating whilst doing it because lots of things can go wrong - but eventually worked out.
Dave

sorry havent got a 2g surf to look at - I'm not even sure if it matters that much in doing that step. One time I installed windows I'm sure it changed it automatically.

Apart from that did you manage to do anything else?