Are you first loosening the Presta valve then burping it to let some air out BEFORE putting the converter on? Other then that you shouldn't have any problems, the air chuck just slips on like you would doing a car tire or mtb tire.
Since I leave my converter on I use it as a valve cap, so I have to remove it first, loosen the presta valve, burp it, put the converter back on, then when done take the converter back off, tighten the valve down, and then put the converter back on.