GFCI outlet/switch combo installation?
This is how a typical receptacle/switch combo is wired.



A combination GFCI/switch, is going to have a different terminal layout.  First, the switch terminals are no longer on the device. Instead they're a couple wires shooting out of the device.  

Next you'll notice a set of terminals labeled LINE, with a brass terminal on one side, and a silver on the other.  There will be another set of brass/silver terminals, but these will be labeled LOAD (these are typically covered by a sticker).

When wiring the GFCI/switch combo, it will look something like this.



The challenge you'll face, is determining which black wire is "hot", and which is "switched".