I'll try to explain as best I can without pictures. I'm no pro at this; it just worked for me. And you may break a couple like I did trying to do this.
Put the clearo in the battery. Take out the outer mouthpiece but leave the rest intact. Hold the battery in your palm and make sure you're holding the metallic connection part of the battery with your fingers (some people have actually pulled the battery apart). Then, slowly pull the clear tube part off of the clearomizer. I must stress: SLOWLY. I destroyed two because it suddenly came apart and I broke the wiring inside. You can also push the "guts" through with something from the mouthpiece end if the seal isn't coming loose. At this point, you'll have the black O-ring (which you would normally fill through) sitting atop the coil. Pop that off and set aside. At this point it may help to push the coil down too. Next, put the clear tube back over the coil, push it all the way down, and make sure the wick and wires don't stick out the bottom. Now, take that black O-ring that you set aside and put it back in through the top, trying to line up the slots with the wick as best you can, but don't push it all the way down. Fill it, put the mouthpiece back on and you should be good to go. I've found that I can't push it all the way down anyway, even if I wanted to.
When you fill it, the needle may actually cause the O-ring to go crooked. It didn't seem to affect anything. If you're using the rubber nipple-tip thing that came with the clearos, you'll notice that it doesn't go all the way in. That's fine.
This was based on somebody else's mod for the older (I think) clearomizers. It just gives the wick more room to get to the coil.
Also, one or two times when I've tried to fill it, it started to leak out the bottom of the clearomizer. Now, I put the needle in one hole, pull it out, and fill through the other just to make sure that both are open and there is airflow. Just to be safe, don't fill the clearomizer while it is attached to the battery, or it may leak into it and short it out.
I hope this helps and that I wasn't too confusing. Good luck!