How to replicate old LPD filter functionality?

I used to have a perl input filter script that ran from lpd (from an entry in 
/etc/printcap) that would take a raw text sent from a Windows client (over 
LPD/LPR protocol) and store it for later processing by a completely different 
program.  It was all quite simple and did the job.

After I upgraded to CUPS (which wiped out my /etc/printcap...grrr), I'm now 
trying to restore that functionality.  Having looked at the documentation, I 
can't figure out how to begin to equate the my lpd+printcap stuff to CUPS.  The 
farthest I got was putting a "printer" service entry in inetd.conf (and killing 
lpd, which I guess is now useless).

Can anyone offer pointers to a HOWTO that gives simple step-by-step examples 
for doing exactly this simple task in CUPS?

Thank you!

--Morgan