I don't have enough time today, sorry.
Two sets of patches Bill provided doesn't give me any changes
when I have applied them to src on 20020612 or so.
(I am not really sure on this point, I need time to make sure)

The situation I have: (with kbd/screen)

(1) boot.fs snapshot/20020407-1.5ZC   ...  stops at start=0x100000
(2) kernel with -D20020407-UTC syssrc ...  stops at start=0x100000
(3) kernel with 20020314 + 20020313   ...  boot fine

All three boot fine if ttya is used for the console.

So what we have to look at is diff between 
20020314+0313 and 20020407 ?

I have placed the diff at
ftp://ftp.ki.nu/pub/NetBSD/port-macppc/20020314+0313-0407.diff

I have typed following diff to generate above:
diff -ur --exclude-from=tmp/file {20020314+313,20020407}/syssrc/sys/arch/macppc > /tmp/diff
diff -ur --exclude-from=tmp/file {20020314+313,20020407}/syssrc/sys/arch/powerpc >> /tmp/diff

ttyp4:makoto@quick  22:14:29/020616(~)> cat /tmp/file 
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Makoto Fujiwara,