Try this. http://www.dakotadigital.com/pdf/HLY-3016.pdf It will take you to the Dakota Digital gauge that is similar to the Victory version of the same item.
Don't rely on the wiring info as the Victory product may be a little different.
Should this not be enough then contact Dakota Digital and see if they can help you.
All the best,
Ps. This is a picture of my set up, with an extra gauge fitted.