Changing it is a bitch. Its easiest to to do if you change the oil at the same time.
   Take off the top caps, take out the springs, and remove the oil (either use a syringe or put your bike upside down). When its all out, use the hex rod, that you should have. If you dont you will have to contact windwave, and it mite be quite expensive.
   With no oil in the fork, you should be able to see a funny shaped thingy with a hole in the middle. Stick the hex rod into this, and twist. I believe anti-clockwise is faster, and clockwise is slower (but check first). Because it will be harder to change again when you've put the oil in again, give it a good twist, but dont do it too far.
  When you've done all that, put the springs back in, and top up the oil to the correct level. Do the top caps back up and ride, check how they are working.

If this sounds a little too complicated, or you don't have the hex rod, you can try changing the oil to a different weight. 7.5 is standard, so to slow them down, try 12.5 or 15, as the oil wont make a massive difference.