the scanbus option of cdrecord is unlikely to ever work on NetBSD, and isn't needed - on some other systems you need to work out the bus addresses and feed those into cdrecord to actually burn a CD, on NetBSD you don't.
Just forget scanbus, and use cdrecord dev=/dev/rcd0d (or whatever device is your CD burner - you're supposed to know that) and it will probably work just fine (Iit did for me the last time I used it, though that is now a while ago). kre
