For a little project my wife is doing for work, I yesterday made her a nLite slipstream with Win XP SP3 and current updates. So basically a XP "SP4" install medium, with a volume install key. This will be applied to 15-20 T61, T400 and T410 machines for users at a conference. For some reason XP was preferred for this specific use, even on these newer machines. To make the numerous installs even easier and faster, I was considering making one slipstream medium for each machine type, with the System Update file for that specific machine, and probably also the LAN / Network driver, in case XP doesn't contain that driver for these newer machines. Then the machines can pretty much get the system software on their own, with minimal intervention from the IT staff.
The question that arises is: How do I apply these two Lenovo drivers/files to the nLite slipstream? When you download these, you need to extract them before you can install them. I assume I extract them first, and THEN apply that entire extracted folder to the slipstream. Or do I select certain files from that folder only? Or what is the correct procedure for this? I can spend the evening messing around with nLite to see what method works, but in case somebody here has tried this before, I see no reason to invent the wheel over again.

Thanks for any input!