Two Exchange mailboxes from Outlook 2010 client

Hi,

This question is similar to that discussed in

http://social.technet.microsoft.com/Forums/exchange/en-US/9405bca7-c2be-47c0-bf94-bdda28e8f7ae/exchange-2010outlook-2010-one-user-needs-two-mailboxes

but slightly different.  I need to be able to access two Exchange mailbox accounts from one Outlook 2010 client.  The problem is that the two Exchange accounts are in different organisations with no federated trust relationship between them.  One account is on our Exchange 2010 server and part of our native domain, the other account is on an Exchange 2007 server hosted by a partner organisation within their own domain.  The "remote" mailbox can be accessed without any problems using OWA but I would like to add it to Outlook as an additional mailbox and manage it from there.

Is this possible?

Simon Palmer