(1) solo the midi drum channel(s), then export. When you're done, you've got a wav. Import the wav to the audio channel(s) you want.
(2) solo the midi drum channel(s), and record audio on the track(s) you want. I do this with my VSTi's all the time.
Don't know which way's better. Anyone?
In either case, don't forget to mute the midi channel when you've got the wav imported. And dropping the VSTi from the VSTi panel will save you some memory.
This is all with Cubase 5. Don't know what's different with SX.
Jay