You can get device manager up with keyboard only, but you are right navigating like that sucks! If you want to try, bring up device manager and then update driver on missing USB Device, then choose from list of already installed drivers/devices and you will find the USB drivers in the list as I've seen someone that had to do similar before.
Or you could try now, is a repair install of XP. That should go over a bit more smoothly, be sure you hit repair on the blue screen where you choose disks to install to and it says windows already there, not the black screen asking about repair console.
If that doesn't work you could try replacing that file (And all USB Files) back into the windows directory manually, from another system with that disk connected as a spare.