I managed to figure out how to access the program myself - via trial and error.
(buttons 1 - 5 are from left to right, with the center button being labelled manual regen)
Step 1) Unplug and plug in the unit (power cycle)
Step 2) Hold buttons 1 + 5 as it boots
Step 3) You will be prompted for a password - I tried a lot of combinations and after 3 tries it kicks you out. My password was: button 5, button 5 (I assume some installers will change this password)
Step 4) You are prsented with two options: Install Setup & Maintenance Setup
I picked install setup and was able to navigate until I found the drinking water setting, and reset the alarm (FINALLY) for another year
I was also able to modify the hardness settings too. I don't recommend messing with the settings too much, as it looks like you can make some changes that will really impact how the unit operates in a negative way.