I don't imagine there will be many tutorials around -- DS 3d hacking is not the most advanced compared to even some later systems. I would certainly not expect to be downloading either a convertor or import plugin and going to town with blender or something any time soon if that is where you were heading.
Still Mario 64 DS has seen some hacking done to it, and tools made ( http://kuribo64.net/board/forum.php?id=32
and some of the new super mario brothers people do things as well).
A quick scan says it uses a somewhat precursor format called to the NSBMD we normally see in 3d games on the DS. Offhand I don't know how similar it might be to the ones we saw on the gamecube, wii and whatnot but between http://kiwi.ds.googlepages.com/nsbmd.html
section 15 of http://hitmen.c02.at/files/yagcd/yagcd/frames.html
you should be able to figure out something. I don't know offhand is SM64DS editor is open source but if it is then it might be able to tell you something about the files in question.