PL-2305 chip not working out
I have been trying to use the Prolific PL-2305 USB to parallel chip to get this done. Unfortunately, the data sheet does not mention the vendor-specific commands required to properly control the parallel port beyond simple printing. It only mentions that the commands exist, Prolific tech support has not responded, and reverse engineering the chip has proven beyond my patience.
Fortunately, Lucent makes a chip, the USS720, which I am already using in my Belkin printer adapter. It will be much simpler to implement since the vendor-specific commands are well documented. Unfortunately, they are a little more expensive, and more difficult to find. They typically appear in name-brand adapters. Either way, they aren't too expensive, and it is worth the time saved.