Hey-Hey!!!, W/o a schematic, the best I'll be able to do now is to tell you to bug ASL until they provide you the instructions. If they won't support their products, I can't imagine you'll be too pleased with them. Good luck, it should be no big deal for them to provide you with what you seek.
With a schematic, I am sure we can figure out how the meter works, and what exactly it is measuring. cheers, Douglas