Don't agree on that. A 68030 will do just fine to start with, a 68040 is not required for this. 16 Mb memory is then indeed the minimum. And the MakeCD program that is referred to is far from 'antique' !!!
So you have not many options. You can try to find an ancient scsi cdrewriter, external or internal, and connect it to your scsi controller. Upgrading to kickstart 3.1 might be better but I don't know if this is required. Another option is the following : you get yourself an IDE-to-scsi adapter, made to connect an IDE harddisc to a scsi controller. It's not very cheap but the IDE devices you can connect ARE !! No problem to get a 52x CDrewriter for 40 euro's !!!
About the burning speed now. Ofcourse it will be way slower than on modern pc's but there is also the safe option of 'burn proof' that all new cdrewriters have, so that it won't matter how fast or slow your processor is !! I don't know if this means that you can burn with a 52x CDrewriter on a 68000 A500 with an IDE controller, but it will certainly work on a 68030 !!!