Um, well I can tell you the first step: you grab the outer ring and pull it off forwards. When you know that it is possible it is fairly straightforward. The ring clips onto the handset part with strong clips: they're not easily breakable, so just pull. You might need to turn it to a different position to make it easier, but it does just come off.
Once removed you can see that the part with the nozzles in and the handset separately. However... I have never got any further than this. Whatever I've tried to pull the nozzle plate out of the handset doesn't work. Given the design of the clips on the ring part, I'd guess the nozzle plate has something similar, but I can't work out how to free it.
Good luck. Post here if you work it out!
Nosport, October 2012