I don't understand what are you trying to do, but I'll try to answer anyways:
If you want to put some animated .m2 file in Blender:
- Convert the file to .m2i with
M2Mod Redux- Download 2.73 version of Blender
- Go to the "user preference" option and integrate the .py files (you can find them in the M2mod folder) as addons
- Import the .m2i to blender
- Do whatever you're trying to do with the file in Blender.
- Export it back to .m2i from Blender
- Use the tool again to convert the file from .m2i to .m2
- Profit.
BUT, if you know how to do this and you're asking about some magic tool capable to edit the animations of the model, you can try to convert all the animations from one model to other one with
this.