I think anyone who can help you will need a little more information to
go on. What happens when you connect the printer and try to use it,
beyond "how to install".

When I've installed 7.10 on my primary Linux box last week, my HP 3940
printer simply worked, with no effort on my part. I'm not sure what
would have happened if it had not been connected during the install,
but probably the same thing, as odds are it was turned off during the
install, since I keep it shut down, no paper, and the front closed
when not in use, as my cats play around with the paper and reach in to
feel the internals if I leave it open and unguarded..