http://www.backglass.org/duncan/ps60...l/ps60_027.jpg

This is your fuel ...

http://www.backglass.org/duncan/ps60...l/ps60_040.jpg

and this is your high pressure oil system. If you are leaking at the oil line than that can't be fuel. You couldn't even see it's leaking, only if you run your engine and you have a visual on it. But if you do, that would mean you have a major HP oil leak, and your injectors wouldn't fire. So that makes me think ( because mentioned that you know, see that you leaking fuel ) that you have some damaged injector O ring, that's why the fuel leaks back to the valve cover.
In this situation you have to pinpoint which injector leaking, pull it and I think you end up faster if you just get the O ring at the dealer...