The CIA in question (which does have to be installed in SysNAND btw, you'll need an internal card without EmuNAND installed) also unblocks the Acekard 2i. If a DSTwo would just break your budget or something, at least do yourself a favor and pick up a cheap Acekard 2i or something that has (or had, anyway) proper support.
I don't even know how you would get a cheat file to work on the blue card. And unfortunately, they're not just for cheating in the traditional sense. You need some just to unlock stages and features in some games. Final Fantasy III for example. You need the cheats to bypass the need to send actual messages online (it's a pain to actually take a DS or DS mode online with it not supporting WPA2, maybe not even WPA -- I certainly wouldn't put my main router to WEP, and while I could probably use my IOGear Mediashair to get it to work, the point is, it's a pain). Without the cheats, good luck unlocking Onion Kid class. Geometry Wars has a stage that is unlocked by synchronizing with either the GC or Wii version of the game, I forget. Anyway, it's a complicated process getting that stage to unlock without the cheats. And then there's Zelda: Phantom Hourglass. I don't even consider that game playable without the control hacks, any more than I consider Diablo II playable without my pseudo-direct-control AHK script and Xpadder (the Phantom Hourglass hacks were actually the inspiration for that, now I don't have to stop half an hour into D2 because my wrist is killing me). Anyway, whoever had the bright idea to bring that horrid and outdated click-to-move control scheme to Zelda should be chained and flogged. OK, someone finally put out a direct patch you can get from RH for that one, but there are many others.
Anyway, the point is, don't be a total cheap-ass. There are many DS cards with actual support from the manufacturer that get unbanned by that CIA. Many of them can be had for $10 or less now. Spend a little bit of money and you'll get a lot more functionality. Just my $0.02 worth.