its a good couple hours of work, but its a dirt cheap project, good for practicing those case mod skillz.
Step 1: Gather Materials.
As far as tools, you'll need a hot glue gun, a screwdriver, and various cutting and prying tools. i found a dremil tool very helpful for some parts but I'm sure if your creative enough you can figure out something else that would work. speaking of witch creativity is basically a requirement with this one =)
Step 2: Getting the Parts Out of the Mice
if the post that attaches the scroll wheel is kind of flimsy (as in the case of the hp mouse i used) you may want to grab a scroll wheel from another mouse, but its not necessary.
I took the picture after i finished the project so just assume the board is not in either mouse.
Step 3: Prepping the Parts (1)
once you have the board placed where the scroll wheel can fit directly beneath the button on the top half of the mouse, mark out the position where the clear plastic piece that directs the light from the led will need to fit. cut out this aria from the base of the bottom of the mac mouse. try to make the hole big enough that you can hot glue around the plastic piece (note: in a while you will be gluing it directly to the board). after that you'll need to hot glue the board in place, and the plastic piece needs to be glued in place, either before or after (note: the plastic piece has to be perfectly clear to transmit the light from the led. so make sure to glue around it so as not to interfere with the light. The plastic piece cant come out below the bottom of the mouse or it will catch on stuff so place the board accordingly (see pictures)
Step 4: Prepping the Parts (2)
you may need to cut out a concave section into the bottom of the button to fit over the scroll wheel assembly (see picture) because the assembly can get in the way of the buttons. I had to cut off one of the arms of the scroll wheel, sacrificing the click function, to make it fit. I also had to put small dabs of hot glue on the ends of the freshly cut buttons so they could reach the buttons on the board. (you can't see it in the pictures unfortunately),
now make any final adjustments to make the mouse all fit together properly and the buttons function
Step 5: Finishing Touches
now just put everything together.
(Disclaimer: this worked for me but i cant guarantee it will for you, ive messed up case mods before. so just be carefull and you should be fine)
GOOD LUCK =)