They needed some work to remove them and the dog ear versions on my Casino proved to be impossible to remove with any tools I own. I'm still waiting to take it to a luthier to have him take a shot at it.Oh wait.. P90s?? I thought he was talking about hums... if P90s the covers just pop on like single coil pickup covers (and are usually plastic anyway) - I don't think people even bother sticking them on with anything
The covers for the humbucker are tacked into place by two smaller spots of solder which should be removable without impacting the potting of the pickup. There are several videos available online.