Yes, you can set up a Line Appearance on a 9641 in Button Programming, either at a User level or within a User Rights Group. However, this is NOT the proper way to set up 9-1-1 dialing. When an emergency is in progress people tend to make mistakes. So you should set up either an ARS table or System SHort Code, so that whenever 9-1-1 or 9,9-1-1 are dialed (from any phone), the phone system sends that call out the proper outgoing Line Group, which contains ONLY the line(s) that you need it to go out. If you are using the Main ARS table for all outgoing calls, you can edit the Line Group on the 9-1-1 and 9-9-1-1 Lines to reflect the appropriate Line Group. Be sure to make test calls after you change any 911 call routing.
The only question I would have is, "Do you use this POTS line for anything other than 9-1-1?
Thanks to technology, we can instantly communicate across the world, but it still doesn't help us know what to say.