This isn't ganging exactly, but in Premiere you can create "submix" tracks -- a feature more common in audio editing programs like ProTools. In your audio mixer you can send each audio track to the submix, and then you can use the fader on the submix to change the volume of everything passing through. You can also apply filters to submixes. For instance, when I have interviews with three people going in the same scene, I will give each person their own track so I can apply EQ and levels for that track that is specific to that voice's needs, but then I send all three tracks into a "Voice" submix, where I will apply some dynamics (like a noise gate) as well as a little reverb to give it some room tone.
Ben Unguren
Motion Graphics & Editing
http://www.mostlydocumentary.com