Patrolling Work in Progress
As of 0.2.1, you can now designate patrol routes using a special power pole called a "Droid Patrol Pole" which is a red tinted medium-electric-pole (subject to change, with custom artwork..).
The way patrolling works, is a squad originating from a Droid Guard Station will detect a nearby Droid Patrol Pole, and generate a list of waypoints for the squad based on the fact that the Droid Patrol Pole is linked to another one in a sequence using green circuit wire.
Once the guard squad has spawned the first droid may immediately detect the patrol pole nearby and "read" in all the poles connected by green wire all the way to the end, and that squad will forever know those waypoint locations, so you can actually delete or lose poles in battle and the squad will continue to patrol those locations until it dies or you pick it up. Because it's squad-based, you can add more units by hand to a patrolling squad without issue.
As the squad leaves the radius of the guard station, the guard station will start spawning more droids to replace the missing guards (who have left on a patrol mission...) Eventually there will be enough guard activity such that the guard station will always have enough "nearby" droids. This can get messy though, and I might change it to once a squad begins patrolling, the guard station becomes "attached" to that squad and won't spawn any more droids unless that squad dies or is nearby and needs reinforcements.
The patrol pole is unlocked at the same time as many other Robot Army buildings, when you research Military 1.