T27G change programmable key on incoming call

[EIP]

Hi, have a T27G proviisioned via a 3CX pbx. Have a request from a client that wishes to have one of the programmable keys to flash "pickup" on an incoming call whereby they can pickup the call.

I have managed to edit the provisioning template to add the label and functionality to one of the programmable keys when the handset is down but cannot fathom where to configure for an incoming call if its possible at all?

any thanks!

Nell