Configure Rails for previous installation of MySQL

Can you be more specific about your MySQL setup? Does your question
pertain to configuring rails to talk to MySQL database (the settings in
'database.yml'.) or are you talking about how to get rails to use
lagacy tables that following a naming scheme different than rails
assumes? I haven't yet deployed rails with apache...have been doing all
my testing with webrick, I'm just not at that point yet.

If you are just trying to demo or learn rails, you can get rid of the
separately installed Apache/MySQL (unless these are installed for other
reasons). This just adds layers of complexity you don't need while
trying to get your bearings in rails. If for whatever reasons you want
to stick with the separately installed MySQL/Apache then manually
install rails as instructed at http://rubyonrails.org/down and follow
the configuration instructions for getting rails working with
MySQL/Apache.
You should treat it as an either/or/but-not-both situation...that is,
either go with InstantRails(and the bundled MySQL and Apache) or
manually install Rails/MySQL/Apache separately but don't try to combine
the two solutions.
It sounds like you are at the early stages of RoR learning. By using
the InstantRails solution, you can skip configuration headaches and
just focus on using/learning rails. By doing things manually, you
introduce layers of complexity to the learning process.
I'm still learning rails and I have deliberately put off trying to
configure rails with Apache because 1) I'm still a good ways off from
being production ready and 2) I don't need the stress/distraction of
troubleshooting additional configuration stuff while I'm still trying
to learn how to write my own methods.

does this help? or did you get a better idea of what you're trying to
accomplish in the meantime? let me know.

john-scott