I didn't have much luck doing that. I thought that was an obvious way to get a bit more tension in but it gave a really stiff push needed, then bang into the big ring (with no usable trimz).
It's working nicely now.
I think I quite like the levers. Such adjustable, much brakes, wow.
Just push the dérailleur a little higher with your hand then tighten bolt.
Tension should be quite tight, a lots more than usual.
No need for that fancy plastic thing.