Depending on the mail system, forwarding can be set up on the server by yourself or an admin. This would preclude needing to access your mail via Outlook at all.
Assuming you keep an Outlook client up, but check a Yahoo account on a more regular basis (when away from campus, your computer, etc.), you can set up a rule to automatically forward mail after Outlook receives the mail. Tools>Rules Wizard...>New>Check Messages When They Arrive>Next>When received through specified account>click "specified" and select your school email account>next>Forward it to people or distribution list>click "people or..." and select/create a contact that has your yahoo email address>next>Create any exceptions that may be needed>Finish>OK.
~Ladi