I have to admit I don't really understand this one, Pellius my friend.
Just use a cable or watch the Brignole interview that Joswift posted. I kept nodding with enthusiastic approval as I listened to a thinking person explains the ins and outs of what you're doing. I also learned something that I didn't consider until Brignole explained it. I always did the movement with the cable wheel positioned at the very bottom. But if you position it so that it is in line with your hand in the bottom position hanging at your side, though I think it's better to be one notch lower, you even more simulate the strength curve of your side delt. Greatest resistance at the start of the movement when you are at your strongest, and less as you progress through the movement as your leverage advantage decreases. I currently compensate by helping myself with my other hand, sort of like force reps except I would have to do it with every rep, to compensate as I start to generate less force as leverage example diminishes but Brignole's way is superior. I am going to look that guy up and hopefully learn something.
He's my kind of person.
As an aside, I live in Cali at the time when Brignole was competing. When I saw him in person walking into the gym in regular clothes I was very unimpressed. He had a bit of a rep back then so my expectations were a bit high. I thought to myself that it doesn't look like even lifted. When he stripped down for the photoshoot my eyes just dropped! I never wanted to be a big bulky bber being stared at everywhere I went, especially now when the first thing people think is steroids, but when I saw Brignole I thought that is the way I want to look.