asterisk users - Apr 2006 - how to make messages button on ip500 work

What are the configuration steps to set up the polycom ip500 to where by
pressing on the messages button will activate voice mail? I suspect the xlm
language will need to be changed but where.

Also, have one main pstn line going in from main telco with cw call
notification. Every time a second call comes in hear the call notification but
no way to switch to the second call. Is there a way to put that call on the
second line?