ODBC to MSSQL - how?

Hello, I am running an app with InstantRails v1.6 on Windows Server 2003 (IIS6 is turned off, I'm running on Apache w/ MySQL), and I have an ODBC connection setup with "administrative tools > data sources (ODBC)" to an MSSQL db on another machine. How can I connect to that in addition to the MySQL db from my RoR app? I only want to read from that DB, no writing involved. I haven't used ODBC before, so any help is appreciated!

Thanks, - Jeff