Parkling lot keys on Linksys 942 phones

Does anyone know how to program or setup keys on the Linksys 942 phones with parking lot numbers? This is to show lines that are parked there and able to be retrieved from any phone.
Any assistance is greatly appreciated.

This is on Freepbx version 2.8.1.4

Simply set the key up to subscribe to the hint (as if you were monitoring an extension). So if you are using default numbering scheme restrict to two parking slots then subscribe the last two line keys to 71 and 72.

In the extended function on the line subscription:

Extended Function: fnc=blf+sd+cp;[email protected]$PROXY;[email protected]$PROXY