To set up for standing "strip the rack" close grip shoulder presses, you set the J-hook in the power rack at chin level. If your J-hook is like the one displayed in the picture (with a long head base), you'll need to set it lower so the bar won't hit the J-hook (head base) during the movement.
Next, you get under the bar and press to the top of the J-hook so the bar is now resting against the rack. Take a slight step back so you'll have leverage to press into the rack. At this point you'll press the bar up and into the rack at the same time. Try your best to strip the paint off the rack (your gym owner will love this). The harder you press into the rack the better.
This isn't your normal shoulder press because you're not pressing back and over your head; you're pressing forward and away. This will make it an easier movement for those who may be training around shoulder injuries. (Note: If you have a shoulder injury and this still hurts, don’t be a moron and keep doing it. Find something else to do.)
This isn't a movement that you'll need to go really heavy on. I like to prescribe multiple sets of 10 to 15 reps with this exercise. Stripping the rack also works very well for bench presses, close-grip bench presses, curls and extensions.
Training Mistakes:
Going too heavy. This is a supplemental movement for your shoulders. There's no need to try and impress anyone with how much weight you can use on the "stripping the rack" press. Save that for the important stuff like squats and pulls.
Not keeping your abs tight and your back straight. No need to explain this to anyone.
Getting in an argument with your gym owner over the movement. Look, he bought the rack and if he doesn't want you to do the movement, then don’t do it. Better yet, buy your own rack or go to a gym where they don't allow spandex!