Hi GMOO,
Firstly, I’d like to confirm the “alias” in your post means the connected account or a proxy address in Office 365.
If you mean a proxy address in Office 365, I’m sorry it is not feasible to set up an alias in Outlook for Mac.
If you mean the connected account, as a workaround, it is feasible to set up the account in Outlook for Mac. For more details, please refer to: http://office.microsoft.com/en-us/mac-outlook-help/add-an-email-account-to-outlook-for-mac-2011-HA102928245.aspx.
If you encounter any issue when setting up the account, because here is the forum which is dedicated to the issues about Outlook client, it is recommended you contact Outlook for Mac forum to get a quicker response.
Your understanding is appreciated.
Regards,
Xinyu Zhou