com.apple.mcxprinting

I'm trying to use WGM to manage what printers users in our lab have. One of the printers has a duplexer, but I can't figure out how to get that preference into the com.apple.mcxprinting. If it's possible, I'm assuming it should go somewhere under "UserPrinterList-Raw." That's where I seem to find each printer defined. I can't find any documentation (big surprise!!) on what all the possible variables are for this record. Anyone have some advice?