There is a prog called dipstar; which I have been looking into, but from what I'm reading, it won't work on M3 Simply... I hope that's not true, if I find more, I'll let you know!
Dipstar does not work on the M3 DS Simply. Currently the only way to cheat at games on the M3 DS Simply is to use games patched with trainers (not all that many)
Chishm has very recently released Nitro Hax - an Action Replay DS clone. I tested a few of the codes with my Final Fantasy III cartridge and it worked great. Functional with any DLDI compatible device. Nitro Hax at gbadev.org