That's not possible. Outlook supports only three addresses per contact.

Signature
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
>I have a contact who has sent us emails from more than 3 different email
> addresses, and I would like to have them all listed on his contact card so
> that the "activites" are accurate when I view them.