Change ES icon of folder?

Hi All! Would it be possible to change the folder icon inside a system to a specific image? Here is why I'm asking:

My understanding is there is no Super Famicom "system" because it's basically the same as the SNES, but prev on retropie I had two "systems" for the diff sets of games. If I can't mimic that in the ES UI, I was wondering if I could put all the SFC games in a folder inside SNES, and then change that folder icon picture to that of the actual SFC system as a compromise? Even if it's not possible in the ES UI, is it possible in a config file somewhere? Would not want to change ALL the folder icons, just that one with the SFC games in it?

Thanks for any thoughts!

You could always create a custom es_systems for the super famicon, copying the xml part of the snes one and just changing the name and the rompath.

Custom es_system is explained on THE FAQ.