I would have Alan Scott be an archaeologist adventure type in his mid thirties and is from Gotham City who would discover the mystical Starheart and it would grant him the power to become the Sentinel. In my version the power would be in Alan and he would never wear a Green Lantern ring or be connected to them in any way. Alan would also wear his Sentinel costume from the nineties and his constructs would look like they were made of green fire. I think the Starheart could be the reason the "Gods" keep coming to earth (see how i would do it Justice League) and I would have him debut in one of those stories. (see how I would do it Justice League) At some point I would have Alan meet his children from the future Jade and Obsidian.