Pop a gain plug into your channel, and use that for a global gain increase or decrease. There is also a global key command, but I do not know it off the top of my head (I just use the gain plug-in ;-)).
Thanks for both replies.
It get's me wondering why Logic has not developed a 'shift-click or shift-drag' way to do this.
How would I automate the gain plug-in so that the fader is free to tweak?
Let's not forget the much underused (or at least under talked about) gain feature in the region parameters. It may or may not be useful in the OP's situation; but is worth remembering. I know I myself never seem to intuitively think of it or reach for it. It hasn't seemed to permeate the deeper layers of my brain or memory yet