Share (Delegate) Inbox to another user while on vacation?

Share (Delegate) Inbox to another user while on vacation?

Hi there,
I'm trying to share and delegate a staff member's inbox while she's on holiday, but can't even share the Inbox :-(

As a workaround, I could create a rule which marks all mail arriving in the inbox as read, tag it as "delegated" with a tag, and forward it to me instead?

Any other advice very welcome - this is needed TODAY!!!
James