Yeah, I did this before in a similar situation. Umm, there was a Windows utility that set up a printer that took postscript input and then ran it through the Windows-only print driver. Let me see if I can remember.

It's been quite a while, but I believe I used RedMon somehow or another. In particular, I didn't use ghostscript to generate the input to the Windows-only printer. (It may have been used as an intermediate step, but it did not know the printer's native language.) I know that somehow I got Windows to accept some sort of data and have the Windows-only printer driver do the proprietary stuff, but I can't quite remember how now.