Sternoclavicular Joint

I have a friend who suffered a (R) sternoclavicular joint injury over a year ago when falling onto the point of his (R) shoulder in a football game. At the time he said the joint felt like it 'moved forward' and he was unable to raise his arm past 90 degrees. He rested for two games and found that he was able to gain full AROM of the GHJ however still complains that the joint doesn't fell 'quite right' during certain movements. The main movement that exacerbates his pain is eccentric horizontal extension (such as the lowering of a weight during chest press). I have found that although the clavicle rolls posteriorly as it is supposed to during this movement, the movement of the clavicle in the anterior direction on the manubrium is excessive and my friend claims that it feels 'unsteady'. Relying on my quick thinking (or lack there of) I tried to do a Jenny McConnel and invent a taping technique of my own! I couldn't find any info on effective taping for the SCJ so I placed an 'X tape' over the anterior SCJ, anchoring one piece at the sternum and pulling it over towards the medial border of the (R) scapula and one piece anchoring over the right rib cage (approx rib 5) over towards the medial border of the (L) scapula. For the first few sets of chest press, my friend found this effective but as he started to fatigue and move into more horizontal extension the clavicle started to move more anteriorly again and the pain began again. This truly is a strange case, any suggestions on treatment for the SCJ?