Download the instructions on Maximum Motorsports' website for their k-member; it will explain how to do it. However, I've not done it on my tubular k-members from other manufacturers. They don't allow much movement like the Maximum unit does.
You can buy a nice plumb bob from Harbor Freight for pretty cheap.
Most shops with a relatively new alignment machine will be able to see the alignment angles, and figure out if the cradle(k-member)
needs to be shifted.. for example if the left side has neg. camber, and the right side has positive, both in roughly the same dimensions,
then it would be shifted too far to the left.. wheels like this.. /cradle/ viewed from the back. hope this helps.