A dumb Makefile that documents/advertises "we can create it"
(root on gdrom0a version)

0) Internet connection is required to get necessary files.
1) Prepare and install cdrtools-2.* binaries (mkisofs and cdrecord)
   via pkgsrc etc.  (3.x might work but not confirmed)
   The following (standard) commands are also required:
   cat, cc, cp, dd, ftp, gzip, mkdir, mv, pax, rm, sh, tar, touch
2) % su root
3) Extract dreamcastbootcd archive (use -p to get proper owner/group):
   # tar -zxpf dreamcastbootcd-20101010.tar.gz
4) # cd dreamcastbootcd
5) If ftp(1) command in your OS doesn't support "ftp URL" format,
   you could use wget(1) or tnftp(1) in pkgsrc etc.
   In that case you have to modify ${FTP} variable in Makefile accordingly.
6) Put blank CD-R media into your CD-R/DVD-R drive and just type "make"
7) Enjoy!

Note type "gdrom0" on "root device:" prompt, and just type enter
on other prompts (dump device, file system, init path).