Steps:

1. Create nether portal in overworld
2. Note the location of the nether side of portal
3. Reset chunk containing onverworld portal (not just reloading it, but completely resetting it to original state)
4. Make another portal in a different chunk, make sure it links up to the nether portal (If the new overworld portal creates a new nether portal, it will not work, you must make sure that the new overworld portal links up with the old nether portal.
5. Wait more than 60 seconds, or as long as you want.
6. Come back into overworld from portal in nether

You will come back in the spot where the first unloaded portal was.