Hello,

not precisely M4, but if you have the "Freak4" (same base figure) you could use the claws from the free Vincent character. They're morphs, maybe they work with the default M4 as well.

http://www.sharecg.com/v/48588/gallery/11/Poser/SOTOs-Vincent-for-The-Freak-4

 

Best regards,

   Michael