The 4 items needed are alfaobd, a windows laptop with bluetooth enabled, the gateway bypass module and the interface module plugged into the obd connector such as
https://www.amazon.com/BAFX-Products-Wireless-Bluetooth-Diagnostic/dp/B005NLQAHS/ref=sr_1_16?crid=1WM9O7OTYQRMW&keywords=obdlink&qid=1578839940&sprefix=obd,aps,174&sr=8-16
Anything you do with alfaobd will stay even when you remove the bypass module. The bypass module needs to be removed if you ever need to take it in for service. The witech software at the dealers will know the gateway is bypassed if left in place. Just remove it when you are done changing any setting and install the 2 plugs back in the gateway. It literally takes 10 seconds on a 1500. The only thing that will ever change your new settings, is if a tech does a vehicle restore with witech. That returns everything back to stock. Then you would need to change the settings again. Again all this info is available on this forum. If you have never done anything like this before, I suggest you find a buddy who is comfortable doing this. It is not hard but can be a little daunting when you see all the settings in the bcm.