Attitude cable routing

[BadDog]

Finally broke down and took the plunge, regular Juice with Attitude monitor. Installing today and I'm not thrilled with the suggested routing through the door hinge area. Looking around on the firewall, I see no obvious candidates for getting through without cutting and finding a grommet. But I thought I remembered someone on here pointing out an access point. Unfortunately, search didn't turn up anything, and maybe I'm just confused.

So, what's the "best" way yet discovered to route this thing? I'm mounting under the dash beside my brake controller...

[Tough Guy]

I've installed attitude monitors on two trucks, and the easiest place to run the cable is through the main wire harness grommet located in the firewall above and to the left of the brake pedal, just be careful to not scuff the wires in the loom or damage the plug on the end of the monitor cable.

Cheers