I recently used Kilz to "seal" the inside of a canopy I built. I am not at all satisified with the results.
I have used DryLock to water proof a few enclosures and am very impressed with the result. I have a 3 year old 4' x 2' x 2' enclosure that has remained 100% water tight since it was built, despite being moved around frequently.
I highly recommend using Drylock as an enclosure sealer...
Note: Latex paint pigments can be added to change the color. I usually use the grey base plus 2 ounces of black to give a nice medium grey color. Their grey is too light for my taste. The guy at your hardware store may discourage adding the pigment but I speak with first hand experience on several gallons it's fine. It will void the manufacturers warranty, but so will using it on wood.
PS -
The finished textrure will be rough like concrete, not smooth like paint. When painting wood with it I have had the best results makign a thin first coat and allowing sucessive coats to thicken up.