Rails - Accessing another database?

I have installed a Rails application using MySQL with DatabaseA. The My Rails application is a port of the PHP application I wrote earlier, so there is some data in the PHP application database (DatabaseB) that I would like to move. It's not as easy as export / import. I have made some schema changes to the database that will require me to process the data first.

What would be the best way to do this? My ideal solution (in the past for PHP) would be to write another controller and then quickly access DatabaseB and move the data to the new database.