That's not a problem but a request.
First of all: the cIOS versions 222, 223 and 224 are made just to run games from a USB drive rather than from the DVD drive. If you have a problem running the game itself, this is the place to mention it (note: it can also be caused by the loader...currently only uLoader itself fully support cios v5).
Second: for redirecting game data from your nand to "the nand of your FAT partition" (aka: emulating your wii's hard drive to your USB drive), this isn't the place to ask...you should check out sneek for that. Alas...at the moment, sneek isn't quite compatible with cIOS'es yet.
Third: I'm not very familiar with the DLC of the guitar games, but I do know that they're encrypted and contain measurements to avoid piracy. So even if you solve the first two points, then getting your DLC to work is going to have issues, as there is more to handle than "just" copy-paste simple savegames. You could check out rawksd, but afaik, that one also has certain issues getting DLC to work (afaik USB loaders aren't supported until the yet to be released version 3.0, and even then, it requires the game running without any cIOS whatsoever).
So all in all, I'd say: it isn't going to happen.