v.4.5 of custom installer seems to has problem with more than one disc (like in your DRIVER conversion)
My custom of Shift 2 Unleashed ask for disc 0 instead 2:
Schowek02.jpg
and the installation ends with error (without uninstall files and registry entry):
Schowek01.jpg
Can you post proper script used in DRIVER conv.? (its setup.dll works fine with mine S2U conv).