After many days of trying different ways to get my LJ3015 printer working under Vista x64 b 5384 , I now have it working! Here's what I did:

Used my original driver disk for XP 32-bit OS and installed under Vista using Compability mode for XP sp2. At the point during the install when it asked whether the USB printer is locally installed or attached to network, I moved my USB cable from the XP workstation it was connected to, over to the Vista box, and...voila!....it found the printer and successfully loaded the drivers. I then shared it and pointed it back at the CD for x86 XP driver install.
After this, I simply connected to this shared printer from XP, and I now have printing on Vista...!
I am very happy, as this was the last feature I could not get to work. I even got sound working on my WinTV PVR 150 card after several exasperating tries...