There's "additional extension" in the voicemail. If you make mailbox 1111 with extension 1111 and have "additional extension 2222", then when 2222 covers to MM, MM will answer with mailbox 1111.
You can also use a cellular number as an "additional extension" and if a cell phone calls the voicemail pilot, it'll get prompted just for a password.
Next, on page 1 of the station form, halfway down, on the right, there's "Message lamp ext:2222" on 2222's station form. Try changing that to 1111. You can also use "aut-msg-wt:1111" as a key - but it would just light a key on 2222 and not its larger MWI.