Colonists in this mod are more akin to biters than to robots, so there are some limitations there. Initially when I started this mod I did want to do something like you described, putting colonists to actual work, but I never managed to implement it in a way that works and decided to go another route (by placing them as 'modules' in buildings).
I currently have no plans to revisit this, especially not since the release of 2.0 completely broke the mod and all my time is spent fixing things. Maybe at some point I'll take another shot at doing something like this but for the foreseeable future it won't happen.