1. Place your bike on the centre stand - you did keep it didn't you? 'cos you'll need it.
I only have mine for maintenance etc, the rest of the time it's not fitted.   That lovely single sided paddock stand you just purchased is no use here (damn it).
2. Remove the rear wheel (and silencer/can if req'd).
3. You'll need a 17mm hex socket for the top retaining bolt of the shock and an 8mm allen key for the bottom bolt (a 5/16inch key is OK here as it's only half a gnat's penis smaller than 8mm).
It may pay to soak the lower bolt area several times over a few days with penetrating oil, this little baby can be a real sh1# to get out.  Worst case is to heat the swing arm with a blow torch.
I bought a set of allen socket keys that fit in a hex socket that I can use with my 1/2inch sq drive socket set and apply some real force!!  Look at the picture opposite - beats smashing away with a hammer.
4. Put a jack of some kind under the swing arm and raise it until it just supports the swing arm.
5. Loosen (but don't remove) the shock top nut/bolt (17mm socket).
6. Undo and remove the lower bolt (8mm allen key).  The lower end of the shock is now free.
7. Lower the support jack until the swing arm is nearly on the deck.
8. Undo and remove the shock top nut/bolt, keep a hold of the shock as will drop away as the bolt is withdrawn from the frame.  Remove the shock downwards - easy huh?

To install the shock, simply insert it in the reverse of removal and insert the top bolt through the frame and shock top eye.  If you have a CBR shock you will need to pull the reservoir through at the same time as pushing the shock upwards.
Loosely tighten the top nut, whilst still allowing the shock to move freely in the frame.
Raise the jack supporting the swing arm and when the lower eye is close to the swing arm move the shock about a little so it doesn't trap it in the swing arm and continue raising the jack.  It's a little bit of a fiddle to align the lower eye to the bolt hole but is easy enough really.
Insert and fully tighten the lower bolt.  I put a little copper grease on the bolt to prevent it seizing in the future.
Fully tighten the top nut and bolt.
Remove the jack support.
Re-install the rear wheel (and exhaust if you had to remove it).

Job done !!