Personally, that seems backwards. Dextrose shoudl have close to 45 points of sugar per pound (ie 1 lb of dextrose with enough water for 1 gallon of liquid has a gravity of 1.045 on the hydrometer).
Honey has about 35 points per pound (again, 1 pound of honey with enough water for 1 gallon = 1.035). Thus Honey has LESS sugars available for carbonation than dextrose, not more. Most recipes(5 gal) call for about 5 oz (3/4 cup) of 'sugar' for carbonation. In this case, using honey, you should use about 1 cup (about 6 oz by weight)
I don't know if Kolsch is supposed to have more CO2 or not if it is, then more honey. As for carbing with honey, if you want a honey flavor, this usually won't do it.