You will need to use a Resource Editor like
Resource Hacker it's free I use
Restorator - Bome Software - Restorator - the resource editor for customization, localization, and translation. it's not free but has a 30 day trial (if you like it and send them an e-mail sometimes they will sell you a student license which is almost half off that is what I did).
You will want to use a copy of the DDORes.dll and put it on your desktop to modify it.
What you wanted to is replace the icon with your icon then save it which should give you a new DDORes.dll with the original named as backup.
After you have modified the .dll you will need to take ownership give yourself permission and rename the DDORes.dll to DDORes.bak.dll in C:\Windows\System32 & C:\Windows\SysWOW64 these are not the same .dll so don't get the one from System32 mixed up from the one in SysWOW64 do them separately
Follow post #6 from this thread will show you how to do it just substitute DDORes.dll where it says shell32.dll
Basic Networking Information
I have not had good luck with resource hacker some have that's why I use restorator
Let me know if you need more explanation or help with this. If you have the icon post it here and I will do it for you.
Jerry