[rukia]

For root/red123, as long as it's in root/red123/misc it should use that URL for the icon. If that's the URL of the default skin and not the others, simply modify the default skin URL to look in $vbulletin->options['bburl'].'/red123/misc/favicon.ico', the script should still then automatically find the icon in any other directory so long as it's in the misc directory and the URL is provided in the style options. Note that it will always look in the root/path to styles/misc/ area, the default URL is the only one that has to be manually specified. I'll see if I can't find a way to locate the URL of the default skin so no modification is required.