The lower front ball joints are not serviceable. In order to change them, you must replace the lower control arm.
The control arm is held in with one pinch bolt on the spindle attaching it to the ball joint, one control arm front bolt, and two control arm rear bracket bolts.
The ball joint will have to be pryed out of the spindle, or the end of the control arm hit with a block of wood and hammer to free it. Once out, the control arm can be pulled from the cradle by placing a prybar between the two.
Reassembly is much easier than disassembly, but will require an alignment after replacement.
The control arms with ball joints are $141 each list price from Mitsubishi. Aftermarkets may be less, and may have a changeable ball joint available. From Mitsubishi, you must replace the control arms though.