ND, glad they went it without (too much of) a hitch.
One thing to note, covers aren't aluminium. Good covers will be made of nickel silver. Some companies use brass as a cheaper alternative, which causes eddy currents and creates a muddier, darker, washed out tone.
The easiest thing to do about waxing covers is to flip the pickup over, and scrape some wax off a plain white candle. Using a hair dryer or heat gun, melt the wax onto the bottom side of the cover and let it wick in between the base-plate and cover. It'll seep down to the bottom and fill any airspace between the top of the pickup and bottom surface of the cover's top, without affectign the coils themselves.
Covers can cause some pretty bad microphonics, especially when they're nickel plated.. the nickel plating interacts with the magnetic field much more than the "raw" nickel silver does.
One last note, if you can make recordings, post 'em up!
