First you'll have to configure your computer with the right domain name suffix:
http://kb.mit.edu/confluence/x/JgNt
After that, you'll have to put your computer on MIT'S network by using the VPN client:
http://ist.mit.edu/cisco-anyconnect/all
After you have applied the correct domain name suffix, restarted your computer and launched the VPN, Office should activate automatically the first (or second) time you launch it.
Let us know if you have further questions.