Well better late than never. The silicone method does work well but, if you want to remove the covers later you may be in EDITED . I have done this and one coil came out with the cover pulling out the start wire, a rewind was then called for.
A good thing really, as it made me dicide to start winding my own pickups which I have been doing for a year now with great results. I'll never buy a pickup again, but I digress.
The reason I decided to remove the cover was that as I have stated in another thread, metal covers seriously undermine your pickups tone, trust me. And yes, you do need to do more than just put it on as microphonic feedback will prevail. I would pot before ever using silly cone ever again. That stuff sets like glue and then after you get the cover off you will need to spend more time trying to remove all the mess you put on top off the pickup, thats if you can get it off in one piece.
So, save yourself all that trouble and leave the covers to those who don't care about their tone, them that sell em.
1ST warning for language!!!