If you purchase the regular Diablo tuner, then it will just come with the preloaded Diablo tunes.
If you purchase the optional Hemifever Tune, then the install process is below:
Once you get the tuner, you will update it on your computer and then install 1 of the preloaded Diablo tunes on the truck. When you do this, it will save your stock tune file onto the tuner. You then email that stock tune file to Hemifever along with all your truck info (year, make, model, upgrades, gear ratio, available fuel octane, etc...) Once they receive this, they will then send you 2 custom tunes based on your mods. Save those from your email to the tuner, and then plug the tuner back into the truck. The transmission tuning will already be programmed int the custom tunes that they send you. Hemifever will also email loading instructions to you explaining how to do everything I just listed.