All you need is the handle bar mount..

http://gopro.com/camera-mounts/handlebar-seatpost-mount

Actually you don't even need that if you keep the square black plastic mount that the camera comes mounted on in the box because you can just duct tape that to the paddle blade.. You can even trim/saw the square mount into a more triangle shape to fit the paddle neck better.. and you can also tape it to the nose of your board when not using it on your paddle.. What ever type you use on your paddle always make sure you have some thin rope or string attaching it to the paddle just in case it comes off.. and the floaty thing is also a good idea..
Here's an old vid that I once did using that square mount on the paddle blade.. Having it on the blade gets the camera further away and although it's not great paddling with a camera attached to the blade it's not that bad.

DJ

Hi Starlet
I used the black base on the Go Pro packaing the same as DJ above but i trimmed the edges and sanded smooth so that it fitted on the shaft of my apddle not the blade. Worked great and didnt have to much impact on my paddle stroke. I fixed it with plactic ties and put a small off-cut of wetsuit underneath the mount so it would not damage my carbon shatf and fit snug. There is a great You Tube DIY vid that shoes you how to make your own.
Goodluck and happy supp'n