Yeah youtube didn't really help for this year's bindings for some reason... just reviews on it. I figured it out, and you just have to really yank on the front toe section outward and it eventually extends (no unscrewing needed, just pop out the 2 side heel clips). And for anyone viewing this with the same problem, just fold up the padding, it doesn't detach completely.
Sorry to bump this old thread, but it comes up as the first hit on google for "burton cartel gas pedal adjustment" and as far as I can tell the above information is incorrect. Or maybe it was correct for the 2012s but not the 2013s.
After reading this I yanked and yanked on the gas pedal/toe ramp, and it wouldn't slide out at all. I emailed Burton and this was their response:
Yes, the FullBED pads will not be adjustable in length. Hopefully your boots fit well in the binding and there isn’t the need for an adjustment.
Hopefully this prevents someone else from hopelessly tugging on their bindings for 20 minutes.