Trouble burning homebrew DC software

I've been having trouble burning self-booting DC discs (or bootdiscs, for that matter), mostly using the plain files method detailed in so many places (The linux one:

dd if=/dev/zero of=audio.raw bs=2352 count=300
cdrecord dev=2,0,0 -multi -audio audio.raw
mkisofs -l -C `cdrecord dev=2,0,0 -msinfo` -o tmp.iso data
( cat IP.BIN; dd if=tmp.iso bs=2048 skip=16 ) > data.raw
cdrecord dev=2,0,0 -multi -xa data.raw

)

I've tried a handful of methods:
Most of my attempts were with the win32 build of cdrtools (cdrecord), starting with plain files.
I also tried SBInducer's cdrecord method, and its Nero DAO method (Nero refuses to burn CD-XA for me), and I also tried having it make the DJ (.CDI) image, and burning that with cdrecord myself.

The symptoms are by and large the same: I put the disc into my Dreamcast (Dreamcast "Sport", Jun. 2000, NTSC), and it plays it like it's an audio CD (Odd thing: As I understand, 300 blocks of blank audio is 4 seconds, but it always shows six seconds)

Most of the attempts were with burning DCRPG. Towards the end I switched to using dchakker, with no better success. Any help troubleshooting this would be greatly appreciated.