I guess that is a version of Bryan's pressure on the kickstarter method, but I'd need to take all 4 plugs out to take the compression away, in order to do what you suggest. OK if they're already out, of course.
I like the suggestion of, before tightening the adjuster, pushing the tensioner from behind, then releasing, to check it is free to move. On a 750, I don't find the factory method of 15 degs ATDC too difficult.