Customize image display based on specific file properties

I would like to highlight any files in the browser that are no longer being referenced by my content management system based on my own custom logic.

I understand that I can modify the GetFilesCommandHandler and the GetFoldersCommandHandler to inject new attributes into the response xml based on my own custom logic, but I cannot workout how to then use that custom attribute on the client side to set a specific css style for any files with that attribute set. This capability would allow the users to quickly see which files are being referenced by the CMS and which files are not and therefore delete any files that are not being referenced.

From what I can tell, all the css styling appears to be in the ckfinder_ie.js obfuscated file and I cannot edit this.

Is there a way to parse the xml response and set a specific css style for each file based on whether that file has the attribute set?