There are two ways to program a Combo Key (talk and listen on the same key) on a Eclipse enabled I-station using ECS software in the Panel Programming screen. 
1.  Select a talk or listen key in the available key types in the bottom section of the panel programming screen using the mouse pointer and place the key label on a blank (unprogrammed key) in the I-station panel mimic.  Place the mouse pointer on the key label and press the right side mouse key, this will provide a drop down list of options for the key label, select key activation and scroll to the orange talk and listen key option and press the left hand mouse key.  This will change the current key type to an orange colored key which is the color for a Combo key.  Apply change to send the change to the frame.
2.  Select a talk or listen key in the available key types in the bottom section of the panel programming screen using the mouse pointer and to program a Combo key (Talk and Listen key) press and hold the keyboard “Ctrl” key and then select the Talk label and place that onto the panel mimic.  This will create a Combo key on the I-station blank key.  To complete the key programming apply the change to the frame. 
The Combo key allows the user to select to either listen or talk using the same pushbutton rather than using up 2 separate buttons one for talk and the other for listen. See the I-station manual on how to " To activate the “monitor mode” of a talk-with-listen key:"http://www.clearcom.com/product/digital-matrix/user-panel/i-series-panel