Use the Robotics Expert perk to make them follow you until you reach a settlement, then enter in workshop mode to move them to any settlement you want.
You can also use the robot workbench to modity them.

*NEW*
MODIFY THE LEGS AND THE PAINT
CAN RECUIT KL-E-O AND IRONSIDES AND OLD RUSTY

NOTE/BUG:
SARGE CAN'T LET YOU USE THE ROBOT WORKBENCH.
SARGE NEED TO BE KILLED TO COMPLETE OLD GUNS QUEST ..... SO IF YOU CAN'T USE CONSOLE COMMANDS YOU CAN'T RECUIT HIM.
IF YOU MODIFY THE TORSO IT ILL BE BUGED AND YOU CAN'T CHANGE IT BACK.