Which loader you use shouldn't matter as long as it can tell the game which cIOS to use when it runs.
What I would recommend is to get ModMii for Windows and give it a syscheck log of your Wii and it will download everything you need to put the right versions in the right places and tell you what to do with them in a very step by step manner.
Sorry for my typo there, I meant 38.
Anyway, to be clear a cIOS is a modified version of an original IOS. The IOS base of a cIOS is which one was modified to make it in the first place. USUALLY you're supposed to have a modified 37 installed as 222, 38 as as 223, and 57 as 224 and it's COMMON to have a modified 56 as 249 and 57 as 250 but I don't know what you might have at the moment. If you go through the ModMii update process, though, you WILL have them installed in those places.
You just need one that's BASED off of 38 or 57 to run that kind of game because they have USB instructions in them that those games use.
D2X is just the name of recent versions of cIOS 249 (after rev21 IIRC) If you don't have v9 or v10-alt installed of that you'll just have to make sure your USB microphones or instruments are plugged in before you start your USB Loader program (like WiiFlow, Postloader, uLoader, GX, CFG, NeoGamma, etc.) and not unplug them until you're done with the game.