Based on the 650MKII
Best results is doing this in an empty car park during the day.
Switch the alarm off. Press G5 three(3) times. Then press * (single star). You're now in the menu for the full sensor for the likes of rain/wind hitting the vehicle.
Use the Boot button to increase sensitivity and the *(single star) to decrease. The alarm will chirp/beep with every adjustment, it'll get higher and lower with different setting.
Next press the **(double star) button. The alarm will chirp once. You're now in the menu for your warn away zone. Stand as close/far away from the car as you want the sensor to pick up. Each time you adjust the sensitivity up or down it will chirp higher or lower depending which way you're going. If you're within the sensor array, the alarm will give the "ergghhhh" proxy noise. If you're standing at whatever distance you're comfortable with and the proxy noise is not going off, then the warn away sensor is not picking you up so you either need to move closer or increase sensitivity.
When you're happy with whatever way you set it, press the lock/unlock button to lock in your settings. The alarm will chirp twice if they're locked in. Then press it again to leave the menu. The alarm will chirp 3 times to confirm you've left the user mode.
Alternative:
Best option is to turn down the sensitivity. If you hit G5 twice and then press the boot button it will fully arm with the exception of Proxies, Omnisenser and glass tamper.
The alarm will still go off if there's an impact to the bodywork, ignition tamper, door lock/handle tamper, bonnet tamper, boot tamper or tilt sensor or power interrupt.
You can still have blackjax enabled.