The ultimate solution is found at
TubsJackson. A bit of backstory: I've been very frustrated with sticky pads and crap alternatives that ruin the helmet, so I designed and manufactured my own solution and I have started selling them (to great success). They are mechanically fixed, ie you can remove it when you don't need the intercom. I've manufactured them with a company in the midlands using a sophisticated 3D printer so they are very durable and stable in the harshed weather NE Scotland could throw at me. I've done 3 types for the EDGE, BOLD and FREECOM intercoms from Cardo.