Step 1: Tools
-A Dremel Tool
-A Clamp with Rubber tips
-Instant Krazy Glue (WARNING: Made a small but permanent smudge on the back of iPhone where it touched.)
-SoundClip by Ten1 Designs
-Slider Case by Incase
Step 2: Anchor Down the Case
Then placed the clamp in a vice to keep it steady, allowing both hands to better control the Dremel.
Step 3: Bore Out the Hole
As you get closer to the right size start taking the case out of the clamp and put it back on the iPhone. Try "inserting" the SoundClip to see which parts of the case still need a little cleaning-out.
Step 4: Glue It Together
Cut out some paper that will fit inbetween the case and the iPhone. and proceed to attach it along with the SoundClip as well. The SoundClip normally hangs on by sticking 2 prongs into the "socket" of the iPhone so go ahead and push those prongs through the paper.
The key here is to get it sitting as naturally as possible. Once glued, it will be permanent, and you don't want it to be crooked.
(Before Gluing, check the Tips and Warnings below)
Once ready, place glue in TINY amounts in the areas that the SoundClip is touching the Case. It's not shown but i used a toothpick to help with getting it in the small spaces.
WARNING Don't use too much! the paper will help keep the glue from touching the iPhone but it's not a guarantee! the brand i used bled through and still touched the phone, causing the previously mentioned permanent smudge
TIP If possible, glue only around the Cup of the SoundClip. I didn't realize until after it was all done, but leaving the "socket" part of the clip unglued allows it to flex when inserting/removing the case. Saves damage to the iPhone and/or the SoundClip down the road.
Step 5: Let It Dry
When removing the paper there will be some sticking to the glue, but it is removable.
Personal Experience with the SoundClip:
It makes the volume only a little bit louder, but the bigger difference is in the clarity of the sound. It's a lot more crisp and clean when the clip is on.
I strongly recommend the SoundClip for anyone with an iPhone 3G.