Hmmm,
can you expand on your question?
It seems like you are asking if u can mix MP3's live with a software program and at the same time u are mixing these MP3's, its burning it to a CD-R at the same time!!!
If so, that's pretty much impossible, unless you have an external home-audio cd-burner like a phillips or sony, in which u would use your line out on your sound card, to the input on your home-audio cd recorder and record live, but I don't even know if that's possible.