In short, NTBACKUP doesn't support backup to CD. I've seen it used along with some other software, but it's severely limited in function and size.

The answer? Find another method.

Here, I use CDRW disks. In Nero I erase the CDRW, then record up to 700MB of My Stuff. To ease backup, I keep all directories of My Stuff in less than 700 MB size.

Works fabulously.