Thread Cubase SL3 mastering

Hi

I have a few songs which I want to send to a mastering studio. My only means of doing so is on a CD (I don't have a DAT etc). A lot of studios would seem to prefer to receive material at the bit and sample rate of the original recording, which in this case is 24bit 48Khz. Apparently it is possible to put them on disc as data files rather than as dithered audio tracks after mixdown but I'm not sure how to go about it. Can anyone tell me if there is a simple way of doing this or will I have to go the audio CDr route? The tracks are a combination of audio and VSTi and I'm using Cubase SL3 on a system running XP SP2 with dual 3Ghz CPU , 2 Gigs RAM and one partitoned 750 GB HD.

Thanks