Not really sure how to achieve the same result without a bench grinder... Rubbing it against the sidewalk might take about 3 years. Oh yea! A file!
Then I took the lipped end to a bench grinder and sanded it down and roughed up the whole piece to make it not such an impossibly tight fit, this is designed to be removed after all!
I also smoothed the edges and roughed the whole thing up to make it slide in and out easier- just remember it needs to be snug, but not too much that you can't pop it back out from inside the elbow.
Make sure to trim an equal and even amount from each side, it'll sit askew otherwise.
Next, after you've got the wall mount where you want it and the notch on the bottom of the wall end, you'll need a similar notch or hole in the wall mount so it doesn't pinch your cable!
Time to hot glue or PVC cement, your preference. Test fit the Apple dock adapter and your iPhone first. Bulky cases may not allow the device to reach the 30 pin connector when resting on the adapter.
Most people will not be able to use their cases with this, as most cases are too bulky. The vast majority of all docking stations out there are made for the naked device.
Push iPhone cable completely through the adapter plate you trimmed out earlier. Connect iPhone then slide the adapter up to the iPhone. If you have a case on it you may have to remove it.
The key here is to place the wall mount where you want first, making sure the hole you drilled is facing DOWN