How To Add Machine Id At Setup

[Ghostrider]

I have working partial unnattended XP OEM, Retail and Corp installs which are slipstreamed, then I use xpinstall to install apps, hotfixes etc and then runonceex for final apps, batch and hotfix installs. part of this final phase i use a batch cmd to ask if oem files are to be installed and if so by whom and on what date, however i cannot think how i can add a machine serial number to install into the oeminfo file during install. I have winnt.sif on the cd but i also have a floppy version i can input user info and cd key etc.

Can anyone help me, my mind has gone blank..