I am a bit more on the pragmatic side. If it doesn't cost you a week to apply, I would take my chance and state that you are lacking the skills in said method but you are eager to learn and a quick study so you expect to be able to perform said experiments as quickly as possible.
In the end, it depends a lot if your "soon-to-be" boss is convinced of you and your abilities - or not. If you don't apply you will ask yourself "What if"..
Worst thing that can happen is that they send you a rejection..