Fastest I ever got was with a 15mhz IIgs, Ramfast SCSI/1MB cache with a SCSI to CF adapter. 256k/sec write, 512k/sec read. Too slow for normal CD writing. You'd have to write your own software so maybe if you wrote one sector at a time. Don't know if that's possible. if you have to write one track at a time then I think you're out of luck. Maybe if you had a SCSI card with an 8MB buffer that you could fill and then write a track in one go at faster than the IIgs could normally handle it.

I wrote ProDOS CDs on a Mac at one time. Made up a ProDOS disk. Connected it to the Mac. Started the Mac with the drive off so it wouldn't mount. Then turned it on and used the device copy they used to have in Toast. Made bootable Cds.