I dont have a LL, I am just thinking about installing one, but the hill assist already does this function, so I would rather mod that feature and be less intrusive into the braking system. I think somewhere in the hill assist there has to be a solenoid that momentarily locks the brakes... when you are on a hill. Find that solenoid, and run a momentary switch to it and bam, you'd have a LL.
If the brakes are controlled by software that is scary... I like to think that when I push the pedal, it directly pushes fliud down the lines, I can handle an electronic throttle, but brakes no way!!
I guess I need a wiring diagram and/or service manual for the car, where can I get one?