Firstly you need to take off the existing rubber strap. To do this, insert the tool (provided) between the strap and the shoulder of the device. You should be able to get the prongs on the tool to go either side of the pin. Once you've got hold of the pin, you need to push it inwards (compressing it into the strap), and it should come away from the shoulders of the watch.
When you have done this, put the pins back into the device without the strap.
You can now snap the device into the bike and wrist mounts:
This is a great kit that's easily worth the money (less than £15 - type "010-10889-00" into Google to find suppliers - I got mine from www.blokesstuff.com). It makes switching from cycling to running very easy indeed. Another bonus is the wrist strap. It's similar in style to the old forerunner models, and in my view is more comfortable than the rubber strap.
Rating: 8/10