This is not something a mailbox can handle by itself. You would have to create a separate CRA for each user, their own separate Audiotex greeetings, and a separate System Forward Path.
If you have a handful of users (like less than 20) it shouldn't be too bad... if you have a lot of users it just isn't going to work.
Wouldn't it be easier to just make an operator hunt group that is always answered?