Very easy. Theres a + screw under the the dimmer roller thingo and another between the steering shaft cover (take off the cover and youll see. Pop off the big plactic cover and youll have the bare speedo. There are some more + screws along the top and sides. After getting them off, reach behind and unplug the 3 big plugs and the speedo cable. And there you have it.
Ok, maybe not so easy, but when i was canging my bulbs i did that process about 10 times. It was quite "fun". If you want to really make a good look, have a glance at the old "led conversion" thread that was up a while ago. Or put some "red condom" covers on the lights for a sporty red glow like mine...