The Way I have done it in the past, is find some voicemail ports that you can you or spare and assign them a new greeting definition of alternate set 2 and then go create a New Voicemail Hunt Group and assign those voicemail ports as members but remove them from the primary Voicemail HG. . Next create a another HG but this one will be a Phantom HG. Once completed go to Call Handling, then call reroute always and create a new index of reroute for the new voicemail pilot number you created. go to call routing and find the Phantom HG and call reroute always to that New index you created for the New voicemail pilot number. Now to test record a small greeting that says please press the extension now, on the new voicemail pilot by dialing the new pilot number and then dialing the admin mail box and go to greetings and make sure you press the option for alternate greetings day and night and record that small greeting.
Now you should be able to dial that phantom hunt group and get greeting you recorded. Next go to voicemail and create a Transfer only Box with the Phantom number you created. Go to MN and insert that Transfer Only box into you single digit translation and WAAALLLAA..
Hope this information works for you