If you want to change the icon of your custom library in the windows 7 file explorer you have to edit a file with your favourite editor. I found the file under the following url:
C:Users<username>AppDataRoamingMicrosoftWindowsLibraries<library-name>
There I added
<iconReference>C:usrlocaleclipse_indigoeclipse.exe</iconReference>
after “<isLibraryPinned>true</isLibraryPinned>”