Rather than working on band-assisted pull ups today, I decided to perform some eccentric pull ups. Here's the great thing about the eccentric pull up. It doesn't involve the concentric part of the exercise, that is, the upward movement, if you don't want it to. You're really focusing just on the lowering part in order to engage those muscles. You can make this more difficult if you want to by performing the concentric part but you don't need to. Also, if you'd rather not jump up to the bar you can just put a box next to the pull up rig you're using. Once your chin is over the bar you simply slowly lower yourself back down. Don't try to come straight down as you perform this. You're going to engage your lats the most by tipping back just a little bit so that you feel a little tension in your biceps as well as in your lats.
Onbward and upward!