You add the sterilizer horizontally in-line to the return hose to your tank. The pump that is returning your water now will be sufficient, given it can push the water the extra 8 inches through the UV.
I love Aqua ultra violets they have a ******** wiper that cleans the quartz sleeves, very convenient compared to most. This insures that the UV is getting to the water without any algae blocking it's path. Very asthetic aswell, looks very good. For your tank you need the small 8watt sterilizer this will cover your size and also aquriums up to 200 gals in case you upgrade. I can get you one for 120.00 plus shipping fed-ex. They sell for 134.95 plus shipping most places with the wiper. [edited]
Good keeping...