Way to setup sub admins on multsite

I have a multsite system setup. I want to give a few memebers some privailages of a network admin, but not everything. Sort of a network "manger" so they can manage network wide users and sites, but not mess with some of the more advanced settings. Any way to do this? I've tried a couple of user role editors, but they still seem to limit an roles I setup to just the main site and not the network. Thanks!