First, make sure you have the latest version of EFLive Scan and Tune software (7.3.3).
What year LL8? I have an 02, and what you need to do is go into the Speedometer section and change B0205 and B0201. There isnt a calculator, so I dont know how you can figure out what to change them to, but the VSS part is directly related to the gears and tire size...