Zak is right there.. You can just undo the quick disconnect fitting to get the dive alert above the water line. And when you do that, neither the BC or the air line will leak as they have valves to stop that. One problem might be if you routed the hose through the jacket, you would have to get it out from there to raise it.
I know some folks that get a dive alert from us, and just leave it in a pocket. When they want to use it, they unhook their inflator and pop it on. You may want to practice this a few times as the inflator hose is a little harder to get off and on while under pressure - but not too big a deal once you get the hang of it.
I also had a customer that decided to put on an extra LP inflator hose - about 20 bucks, and also put one of those rubber air blowers on the end of the dive alert.
Then with this hose, they had their dive alert, and an easy way to inflate a sausage without using your octo.