Sadly there are no parts on an 89Si that are adjustable except for toe in and Caster. Caster is related to the radius rod going from the lower arm forward to the subframe or cross member. The chances are that the car will need a frame machine to pull the suspension pick up points back to where they belong if the Caster is really out. First stop is the alignment rack to see just what is damaged.
I do not recommend that anyone attempt to straighten a control arm-much better to replace it.