I have been searching for an answer to this question for the past 6 years and failed. It seems a lot of people are either afraid of getting into their car's brains or just not determined enough. I was even considering building a whole setup where I would read a gps nmea signal, then rather than obd - tap directly into the pedal. And for safety create a hard relay controlled from the brake pedal and also a manual cut-off switch just in case.
I don't have the skills to analize can-bus signals myself to build a register changer, and not determined enough to go with my crazy idea.
I was initially considering either buttons that have preprogrammed 59, 69, 79, etc values, or even better - a number pad so I can punch in anything I want.
This thread is so far the first I found anyone other than me even requesting such functionality 