Has anyone managed to remove/replace an ignition switch on their '68 without removing the instrument cluster??? From the looks of things under the dash, it can't be done...or can it...

Sure, you just need to get a hand up there to disconnect it. I've done it many times.

With just a small amount of luck, the wires might be long enough to let it drop down. Once it's past the lighter itsa free fall!

What's the trick to disconnecting the connector on the back of the switch?
Is it "locked" on there somehow? I had it out once before when I had my entire dash apart but for the life of me I can't remember how it connects/disconnects...

Also, should I remove it from the dash first and then try and disconnect the fitting on leave it mounted in the dash for stability while trying to remove the connector?

There are 3 tabs, equally spaced around the switch, you gotta push in on each tab, then pull that side out far enough so the tab doesn't lock again when you do the next one. Can be a real pita on your back in the dark.

I would try to drop it down first, it just might go low enough to see it and reach it better. If not, you might end up screwing it back in the hole just to get some leverage, the connector is a tight fit.