Has anyone successfully made their own user defined condition or event?

Basically I'm trying to make a cute little editor to quickly tweak MR settings and I'm trying to create custom events in order to dim/enable controls based on whether or not certain MR features are on/off like FG, caustics etc.

I made a global proc that queries and returns a boolean value but I'm having trouble getting the condition command to use that script.

The documentation uses pre-defined dependency conditions in the example (and I can't find those to find out exactly how they went about writing them, like "SomethingSelected" and "UndoAvailable" etc). This is so frustrating because I really thought it would be simple enough, maybe I need a break. Sigh*