As Jeff described, the installation is pretty straightforward. Both Shimano and Microshift levers work well. However, some things to keep in mind during the installation:

1. You have to remove the shift levers from the bodies to install the bodies in the barends. Be careful to keep all of the shift lever parts (levers, washers, indexing plate, etc.) in the correct order and orientation so they reinstall properly. This is particularly important for the rear (indexed) shifter.

2. The fixing bolts that tighten the bodies into the bar end will tighten "backwards", i.e. counterclockwise. They are really right-hand threaded but you are working from the end opposite of the head.

3. You can run the cable housings under the bar tape just past ends of the flats and then have them emerge from the tape and loop externally to the downtube cable stops OR you can run the housings under the bar tape around the bar all the way to the stem and have them emerge like current STI housing. The first way theoretically shifts a bit better and the second way is more convenient and looks neater. I've done both and both ways shifted just fine. There should be Youtube videos showing the cable routing alternatives.

Finally, are you sure you want to do this? I've had bar ends on three separate occasions and always found them inconvenient. As an alternative that lets you sweep the entire cassette and offers friction front shifting look at Gevenalle (gevenalle.com) shifters. These are dedicated brake levers that use the shift levers from downtube or barend shifters but put the shifters right on the brake levers. They are as convenient as STI's but more rugged and versatile. Since you plan to buy the shift levers and new brake levers anyway, the cost difference won't be that much. I now have these on four bikes and wouldn't go back to any other type.