The attachment in the OP shows how to adapt the switch(es). It's pretty simple. Dave's image on top of page 2 shows the harness side.
Like most any cruise control, you need an on/off (toggle) and a set/resume (momentary). It's literally $10 worth of switches from Amazon.
Two switches is all that's basically required. I personally would avoid any wireless solution like BT (but the BT switch Berend used can be easily found on the Internet). To hard wire it, you either dash mount the switches or you can use a spiral cord to connect the switches on the wheel (like the old telephone handset cord). To use a cord method, you run one side thru (typically to a removable plug fitting) on the dash, then the other side to the switches on the wheel. The cord will wrap around the steering column as the steering is turned and unwrap as steering returns to center. I've used this cord method on the p2t mic switch steering in my offroad cars for decades. It's actually a very clean look/install.
But the cruise feature is disabled by default in our trucks. You then need to flash the ECU to get the feature activated (CAT can do that for you). That can be the most expensive part of adding the cruise. Some users here have the means to flash it, but you have to send them your ECU.
You'll also want to tie in the brake switch for disconnecting the cruise.
I can't be of much help with the specifics on the A1R. I've not actually hooked cruise up in my truck yet.