In which forum should I ask Compaq related questions?
Forum: Printers from other manufacturers 
Where can I find a table of working Compaq printers?
Which printer is this similar to?
This is probably a remarked Lexmark Z22 printer.
Which driver do I use?
Usually, Compaqs are relabeled Lexmarks. So you should try drivers for
Lexmarks with the same maximum resolution as your Compaq. Either free
drivers as listed on openprinting.org or drivers provided on http://www.lexmark.com/ 
for various models.
If at all possible, use free drivers. The lexmark drivers
cause a great deal of problems, and do not work with free
software like CUPS.