Here's how I did mine:
Sending unit removed from tank
Remove trunk pan body plug to allow the sending unit connector wire to be routed into your trunk
Hook sending unit up to sending unit wire and attach another ground jumper from the body of the sending unit to a good ground (lay your sending unit on a piece of cardboard or something non conductible)
turn on key to power up your gauges
Now with the unit hooked up you can swing the float arm through its full range of motion and check to see that your gauge is reading correctly. You can also make adjustments by carefully bending the little full/empty stop tabs on the sending unit arm.