Odysseus wrote:
[...]

I also find it insulting that the Mac OS 9 clients put up a message
saying we should switch to BOINC when there's no version of the
software for that platform.

Try this comment:

"With the tool XPostFacto is it posible to install MacOS X on older Mac's which are not be supported by Apple. I don't know, if it works very well. But sounds very interesting.
See also my posting http://setiathome.berkeley.edu/forum_thread.php?id=19073#211847."

Good luck,
Martin