When the Rendezvous enabled version of iTunes comes out, you will only be able to stream mp3s from one computer to another, not burn a cd from one to computers library on another.
What do you want to play the disk in? A consumer cd player with mp3 capabilities? If you just want to play them on a mac, use Disk Copy to create a blank cd image. Then open iTunes and then drag and drop the songs to the cd image. Then copy the image from one computer to the other, then you can burn the disk image.
If you want to play them on your car stereo, then you will need to copy the songs to the mac with the burner. You could either use the method above, or copy the songs to your public folder and turn on file sharing.