I've not had a chance to shoot photos of how I do it yet, but to decrease preload, I remove the seat, remove the front tray and access the collar from the right side of the bike. To increase the preload, I access the collar from outside the bike and there is what seems like about a 5mm window of optimal positioning of the spanner to the collar that allows you to grip the collar and turn it one click. You must use both hands solidly: one to apply a good force to keep the spanner wrench engaged in the adjustment collar and the other to apply torque to make the adjustment. If you slip, you may have a scratched trellis... Note that the shock rotates slightly and you can use this rotation to your advantage if necessary to get the spanner on the appropriate notch on the preload adjuster. I've never had to use a the hammer/screwdriver method on this shock. Patience to find a good position for the spanner is key.