Well, it was about time I got of my lazy ass and did something so I took a look inside 7-Zip source and added primitive support for external Icons.
It’s still unfinished and it’s implementation isn’t “perfect”, but it’s simple.
I’m still working around it to provide a way to do something like “7zFM.exe /refresh-icons” (done) to make it easy for icon pack authors like myself to distribute their work.
Time will tell if it becomes a base feature of 7-Zip but for now those that want to take an early peak can check the beta, you’ll need 7-Zip 9.04 beta for it to work properly.
Update: I’ve refreshed the files with the addition of the “/refresh-icons” command line option to 7zFM.exe.