If the polygon length of Roy's hair is the same as Marth's then I'd say that it's possible. You'd have to find the polygon in hex on Kirby tho and switch it with Roy's. The only problem is that it is vertexed so I'm not sure if the changes would be found in the hex, tho they might. :\
Honestly I think I remember seeing a Kirby Hat tutorial somewhere here on the Vault.
Thanks

Then i'll try to find it