I just recently had a chance to have a crack at a SD 3.20.020 (Harry Potter and the Prisoner of Azkaban). While not quite the same protection as Doom III (SD 3.20.022), it is extremely similar. Either way, I hope this report helps someone make a backup of a SD 3.2 protected title.
I have two drives at my disposal, a Sony DRU-500A and a Lite-On LTR52327S. Unfortunately, I was unable to make a working backup using the Lite-On. However, the DRU-500A fared much better. Using these settings and media, you shouldn't have a problem making a successful backup:
In Alcohol 120% v1.9.2 (build 1705), select Safedisc 2/3. Use minimum read speed (in this case 1x). Same goes for writing, using Memorex 48x CD-R's.
Using this procedure should result in a disc that will play on the LTR, but not the Sony (which doesn't seem to make sense, but oh well). I hope this helps someone to make a successful backup as this should be applicable to Doom 3 as well! Any questions, feel free to ask.
I'm no longer afiliated with this forum. If you need professional help find me at http://digital-burn.net