Open Door with blf key?


My question is regarding no how to do it, but whats the way to do it.

I have an IP Intercom on Extension 6
While call if i press 00* It will open the door.

Our Receptiont has cisco 514s phone with 500s attendant console which i want to set her a button to open the door.

I am not sure if its can be done from the phone side, i mean automatic.

I am thinking about creating another Extention which call 6 and send dtmf after call pickup, is this the way?
and can you just pin point me on which file or gui part to edit.