I have a Wallstreet II Powerbook running OS X 10.2.8 (and 9.2.2).  I
have recently obtained a Hewlett-Packard Deskwriter 560C Inkjet serial
printer, and have been trying to make it work with that Mac.

Of course, it works just fine in MacOS 9, but OS X does not support
serial printing by default.  So I found some instructional pages about
how to kludge CUPS to add serial printing capacity, and to install
hpijs foomatic which has the drivers of all the supported HP inkjets
(and, since all HP inkjets tend to speak the same language, I should
theoretically be able to use one of them in substitute, assuming I get
my printer and the computer talking to each other correctly).  I also
found out how to plug a serial URI into Print Center.

I even managed to get the printer to notice when I was trying to print
to it.  Unfortunately, the notice it took was printing a couple of
pages with one line of gibberish each and an error message about DTS
flow control.  The person who's been helping walk me through this in a
post to the MacOS X livejournal forum at
http://www.livejournal.com/community/macosx/1726941.html has been
exceedingly helpful in getting this far.  He suggests further
experimentation by twiddling around with flow control, baud, and other
such settings until I find something that works.

However, the printer works flawlessly still under OS 9.  Which means
that there must be *some* way for the hardware to talk to each
other and be understood...and if I can just find out what it is in OS
9, I can transpose those same settings to OS X and save myself some
guesswork.  However...I'm rather inexperienced with OS 9, so I'll be
darned if I can figure out exactly how.  And the fellow helping me in
the LJ isn't much on OS 9 either, and none of my posts to Apple fora
have returned any answers.

So, when you get right down to it, my question is this: How do I find
out what the flow control, bit rate, parity, and other such settings
are for my printer under OS 9?  And is there anything else I need to
do to get it working properly?  (For instance, does it matter which HP
printer driver I select as a "closest match"?)

The fee (and possibly tips depending on how thorough the answer) will
be awarded to the answer that lets me get that information I need.