Yes it is, in Outlook 2003 anyway. Al you have to do is go to the bit where you work with an email address, select "new email address", select "http", then follow the instructions for entering your hotmail account.
When sending an email, make sure you click on the "accounts" button on the message to make sure you have selected the email address you want to use. Sorry the instructions aren't more precise, but my Outlook is in Dutch and I ain't sure that going through it step by step in Dutch would help you!