Sorry, I've been so busy..
I actually got this done and figured out..
I did the same thing @
spinning_Sushi did, but instead I used the trac/vsc buttons from an automatic FRS, since it has 4 momentary buttons.
[ame="https://www.youtube.com/watch?v=VgKLJZlznBY"]FR-S Trac/VSC Rewire Cruise Control Function - YouTube[/ame]