Sorry it's taken so long for these. On top of having one of the most hectic two weeks I think I've ever had in this job (with customer escalations), I tripped over a few things with having to upgrade the SPARC build machine and then having to rebuild my SUNWonbld stuff for both architectures as some things needed updating in it and then discovering a couple of little things I had updated on the build machines and not in my source tree (sigh). Anyway, they are up now.
They can be downloaded from The Download Centre. I've also updated the MD5 Checksums for the extra files.
Note that as of build 54, you no longer need the fiddle to usr/src/Makefile that was previously required to do non-debug builds, so have a look at the new instructions.
Dennis Clarke has also written a great step by step guide.