Should be pretty easy
I agree with those above who have said it is pretty easy.
I am also running 4th Ed in Golarion, and really, all you need to do is fit the races in.
I made the Eladrian elves who instead of leaving Golarion through the gates thousands of years ago, instead retreated to the Feywild. This group was much smaller, so they are not really noticed as different from "true" elves.
I made Dragonborn and Warforged as remnants from the millenniums long war between Geb and Nex, such that no one actually knows anymore who developed which ones first.
Then just swap the Gods. If Players want to take divinity feats, let them pick which one they want, and then they need to come up with the fluff to justify it themselves. I am a big fan of making players do the hard work to fit their 'non-core' concept into the world.
Things may change when the planes material for each is released, but I plan to just make use of whatever planes I need at the time.
