Exchange 2010: Shared mailbox in OWA simultaneously with original mailbox?

Hi.

I just installed Exchange 2010 and am wondering what I should be looking for. I hope you can help me by letting me describe what I wan't - although I'm not even sure if this is possible.

I want all employees to be able to log into their own mailbox on OWA, but I want all of the employees to also have access to a shared mail@mydomain.com mailbox without having to relog. Kind of like in Outlook when you:

Go to the Tools menu, click Account Settings.
Select and double-click the email account you would like to change.
Click More Settings.
Select the Advanced tab.
Click Add to open another mailbox.
In the Add Mailbox box, type the name of the mailbox owner.
Click OK twice.

Doing that gives you a seconday mailbox you can see simutaneously with your original. Is that possible in owa 2010? I know you can open a seperate mailbox by clicking at the top right, but that opens in a new window unfortunately.

I know I could get similar functionality by making a distribution group instead, but storage wise this is very bad having a single email getting stored x20 on each members mailbox which is why I ask this question. Thanks in advance!