Direct to the battery. I like the CB to be always hot so that I can communicate even when the Jeep is turned off. I leave mine on in camp incase a club member is still out on the trail and has an issue (when we break up into multiple groups) and I leave it on at major obsticles but kill the motor (the good spectator ledges and such).

I ran the ground wire to a ground screw by the driver side left foot, near where a dead pedal should be. I ran the hot wire out the firewall on the driver side through the foam tap then over to the battery.

 

How did you drill out the grocery bag plug, What size drill did you use