The hole for the cargo light is relatively simple, since you just need a hole big enough to let the wire pass through. Exact position is not that critical. I already had a dome light, so I didn't have to figure that one out. However, I have replaced mine with an LED light and it seems like its also fairly simple.
One important thing to remember is that these lights are not grounded to the body and you must use the plastic insulators that come with them to keep them isolated. The lights have constant 12 volt power on the orange wire, and they turn on when the white wire is grounded through the headlight switch or one of the door switches. This is the opposite of most other accessory items, which are grounded all the time and the power is switched on and off.
Bruce