I have an old nonfunctional IBM Thinkpad 380xd with an internal cdrom drive, and I'm looking at buying an ultralight that has no internal drives (other than the hard drive). How would I go about modding the internal cdrom drive to run as an external usb drive?

I have a general idea that I would need to cut the end off a usb cable and solder the right wires to the right connectors on the drive ribbon, but which to which? Would there need to be further modifications?