I managed to get daemontools to work on panther from this doc, although it's a tad opague:

http://dqd.com/~mayoff/notes/daemontools/macosx.html

(notice that it's good ole Rob Mayoff, an old aDer)

You should also see this about the fact that launchd is the way to go under Tiger:

http://openacs.org/blog/one-entry?entry_id=296603

Enjoy,

Walter