Originally Posted by SouthArk370Z

While the oil will degrade the hoses/seals over time and can coat some of the interior surfaces, it's not the end of the world.
As per DE-and-a-half:
1) get a baster and suck up all the oil that you can
2) using a funnel and small tube to get below the oil, add some water or antifreeze to the radiator.
3) repeat until you can't suck up any more oil and then
4) slowly overfill to push out any remaining oil. A half-quart or less should do it.

It may help to raise the side of the car that the cap is on so the oil will migrate to the opening.

There will still be some oil clinging to the radiator but it shouldn't be enough to do much short-term harm. I suggest that you change the antifreeze soon to clear out any remaining oil.