To get them to work in Clone, you just need the conversion tool for downloading songs off of C3 and then you’re basically set.
Once the Conversion Tool is open, click PHASE SHIFT CONVERTER. Under Audio (Mogg) options, check Downmix to Stereo. Once that’s done, you just have to drag your downloaded song into it. (it’ll look like a piece of paper) You can do conversions in bulk, just give it a while to load but it’ll tell you found X amount of CON files ready to begin.
Once it’s ready to begin, just click begin and it’ll start converting them so they’ll be playable in CH. It’ll tell you it’s done, so when it is, just find your new song folders and drag em all in your song files for Clone Hero. Something to remember though is you’ll need to make a separate folder for all the songs you download this way and drag the per-converted files into it or else every time you download a new song, it’ll convert the ones you’ve already done with it and you don’t want that