How to wire GFCI combination switch/receptacle
I got it figured out with the help of my electrician friend...

Pigtail hot inbound and outbound wires with one of the hot wires protruding from back of the combo switch. Send the 2nd hot wire protruding from from of the combo switch to LINE brass/hot side.

Take neutral inbound and outbound wires and pigtail to LINE silver/neutral side. 

Obviously connect the grounds together. 

I now have the combo switch operating it’s own outlet and have allowed for power to continue on to the next outlet downstream, though of course passing the burden of GFI protection to the next outlet.