I'm guessing you mean rim clicks here, like Stewart Copeland style playing, no?
If so, there is indeed a different approach needed compared to natural doubles on the drum head. It's more from the wrist and the grip is essential. Don't press too hard on the skin or you'll kill the sound too.
As for speed, I don't think there is a substitution for good old practise. Learn doubles (16th notes) on hihat and rim click with a bass drum pulse on each quarter. Then shift to inverted doubles between hihat and RC. With a bit of time you'll get the required leverage on the stick in order to snap out two quick doubles. Eventually you can try triplets - hihat followed by 2 doubles on the RC (phased both as triplets and 16ths).
Experiment with where you grip the stick too i.e. closer to tip or the butt. This varies depending on hand size and stick etc. If you find the sweet spot of the stick this can make the whole motion much easier.