Need help trying to get a batch file to run in sysprep

What I want to do is to create a batch file that will take user input and edit the sysprep.ini file and add text after the "Computername=" entry so that sysprep will have the proper computer name instead of having this extra step of changing the computer name after the image has been loaded on the machine. This would only work if I could get a script to run before Windows starts to load. My question is does any one know the correct procedure to get a batch file to run before Windows loads and sysprep starts?

I would think it would be:
1)Image machine with ghost
2)Machine reboots
3)Script runs, takes user input for correct computer name, edits the sysprep.ini file adds the computer name
4)Windows starts loading and runs sysprep

Only problem is I dont know which file to edit to put a command line in to say 'hey run this batch file'. Any help would be greatly appreciated.

Thanks in advance,
Casey