You can save yourself a lot of hassle by installing a wireless wall switch. One option sold at home centers or online uses a screw-in radio receiver that installs between the porcelain fixture and the bulb. The battery-powered switch mounts on any wall. Although it's inexpensive, it's not very attractive and only powers a 60-watt incandescent bulb (it won't work with CFLs or enclosed fixtures).
If you plan to install an enclosed fixture or don't want to deal with dead batteries, buy a self-powered wireless switch kit (do an internet search for “wireless, batteryless switch”). The switch never needs batteries. It sends a wireless coded command to the relay mounted inside the ceiling electrical box. You can mount the wall switch anywhere on the wall as long as it’s within 100 ft. of the receiver/relay. You don't need a switch box!
Turn off the power before you install the receiver/relay. Connect the relay to the fixture and the house wiring (see Photo 1). Then turn the power back on and follow the receiver/relay programming instructions. Test the light switch. Turn off the power one last time so you can safely tuck the receiver/relay into the electrical box and finish the installation.