You can get the screw tubing from online retailers like Bestbassgear http://www.bestbassgear.com/pickup-screws.htm
Some manufacturers include it with the pickups like Delano for instance.
The foam can actually be used with the packing foam that is supplied with the pickups like some EMG's, Dimarzio, and Delano's. Or you can go to homedepot and purchase the adhesive backed weather stripping.
Personally I use a dab of hot glue or double side tape to mount the foam to the back of the pickup and use approximately a 1/4 - 1/2" to allow for versatile height adjustment.