Download Resource Hacker
Resource Hacker scroll down until you see this that is the download button.
Always work on a copy of any .dll you modify so you can keep the original intact (I usually put them on the desktop).
Open the shell32.dll expand Icon Group expand 24 and click on 1033 you will notice that the icon is nine layers that is 32 x 32, 24 x 24, 16 x 16, and it is repeated two more times you should try to make an icon that is the same way (if you need help with that let me know).
Click on Action then click on Replace Icon.
Click on Open file with new icon...
Navigator to the replacement icon and click on open.
You should see the replacement icon plus where it is coming from then Click on Replace.
You should see the new icon in its place.
Now you need to click file and then save it will give you the new .dll and it will also keep the original renamed
I do not know if you know how to replace a .dll but if you look at Post #6 of this thread
Basic Networking Information it will show you how to take ownership give yourself permission and how to rename it and replace it.
Jerry