Ruby setup on mac

I followed the setup instructions on hivelogic website for installing ruby on mac leopard. The trouble I am having now is that the default db is sqlite rather than mysql. I don't know how to change my ruby config from sqlite to mysql. Can someone point me in the right direction?

rails -d mysql your_app_name

Is this for a new or existing project?

This is for a new project. You only need to change database.yml if you have an existing project.

Refer to:

By the way, why did you install Ruby from Hivelogic on Leopard. Mac OS X Leopard comes with Ruby built right in. It's what I use and I've seen no problems using it. It's find, but I was just curious.