There is another (older) thread that describes one way how to change the pink icons on the desktop.  I don't know about you, but that was the first thing I tried and the icons that showed up on the desktop never changed.  I got frustrated because the pink icons are really annoying so I did some digging and found a solution.  

First I am using the newest mac osx lion. My pogoplug software version is 3.1.1 (3.1.0.67)

Here is how you change the icon.

• First you need the icns file that you want to use.  I use CandyBar to create this, you can use whatever means you want.
• now that you have your icns, rename it to Application.icns
• from finder, on the menubar up top, click on Go -> Go to folder
• then copy and paste or type this in without quotes "/Applications/Pogoplug/.images" (This folder is hidden so you won't see it)
• Now just replace the Application.icns file in the .images folder with your own....make sure to backup the old one.
• Restart your computer and you are done. 

Enjoy!