That should be pretty straight forward to install. You'll probably have to just drill out the bottom for a hole big enough for the bulb to go through, but small enough yet that the clips on the light adapter catch on the sides of the hole.
A 4 watt bulb shouldn't put off to much heat, but if you're concerned about it. You probably could line the area round the bulb with some of the aluminum tape for sealing heat ducts.
You also may have to groove out a channel on the bottom for the cord to recess into.
To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault