There are certain CIAs out there that are properly signed by the eShop that can run in Classic Mode (but like it was said, you'd have to install them via other methods like using the CFW), but I imagine their total numbers are quite small compared to all of the unsigned ones. So Oishikatta's idea would probably work, though you'd need to somehow move the tickets that got installed from the CFW to the MT emunand. I wouldn't have a clue as to how you would do it, though. You could probably ask cearp over in the FunkyCIA2 thread to get a better idea.
