GSX already supports this feature, which we call "custom parking brakes test", but it's not user-customizable, we have it in the GSX airplane configuration database for the Aereosoft Airbus series and the FS Labs A320 so, with those planes, GSX is testing a custom XML expression (much like the custom XML espressions for the doors), which tests the variable these planes use for the chocks, instead of the standard FSX variable for the Parking Brakes.
If you try one of these, you'll see that GSX doesn't require to set the parking brakes, but the wheel chocks, even if it's still saying "parking brakes" in the message.
What we might add it, is the ability for users to control it, and changing the UI message to name them correctly.