Here's an alternate method I used, using the icons provided by Apple:
[Read through to the end before proceeding.]
Open the registry editor (type "regedit" in the "Search programs and files" text box at the base of the Start menu). In the Edit menu, open the Find dialogue box and search for "Apple iPhone". If the key you find has a value named "Icon" or "Icons", double click the word "Icon(s)" and, in the dialogue box that pops up, replace the contents of the bottom text box with the following:
for black iPhone 4/4S - "%SystemRoot%\system32\usbaaplrc.dll,-117"
for white iPhone 4/4S - "%SystemRoot%\system32\usbaaplrc.dll,-118"
There are several values to change throughout the registry (five on my machine), and not all of the registry keys have the "Icon(s)" value (don't create values in those keys, just skip them).
Hit the F3 button to continue searching through the registry and, every time you find the "Icon(s)" value in a key, edit it the same way you did above. Continue searching through the registry until a dialogue box pops up that says, "Finished searching through the registry." You'll probably have to reboot before your new icon pops up in "My Computer".
Note that, if you have an old iPhone that did display an icon correctly, you'll find several "Icon(s)" values that are already assigned to "%SystemRoot%\system32\usbaaplrc.dll", but with a different number. Leave those ones alone; only change the ones that don't contain the "usbaaplrc.dll".
Hope this works for you!
Thank you.