K-Line and TMCC cruise don't operate that way. You either turn them on or off, select the speed steps 32 or 100 (128 and 200 for K-line Cruise). If you want a higher speed turn the throttle up to the speed you want and then the cruise will maintain it.
It is kind of like cruise control on your car, it is just not set to scale MPH. Only MTH engines have that level of speed control. G