There's already some inu yasha skins up in the skins forum...using those would probably be a lot easier then learning to edit your own models.
But to answer your question, you would need these first:
-A 3D modeling program, such as 3Ds Ma, Gmax or Milkshape.
-The mdx/mdl file converter (on this site)
-war3viewer (also on this site)
-The warcraft 3 tools and scripts for the 3D program (some of which are on this site)
-An imaging program that can support .tga files, like photoshop or paintshop pro
And yes, I liked Inu Yasha...until they dubbed and edited it...ugh...
-VGsatomi