actually I was rather after the magic immunity but I'm not all that sure you can use a templated animal as the base for lycanthropy... besides that it is heavy cheese (more so than playing a flesh golem)
yes its EXTREMELY cheesy, but you can do it.
since an animal that makes the save stays an animal, is eligible for the Lycanthropy template. and since the Lycanthropy template specifically does not use the "level adjustment" of the animal part, the fact that a template applied to the animal with a "LA n/a" (or +0 or more, for that sakes) doesn't matter.
there are several templates like this, that allow free templates (only specific ones though) if applied to the non-mental part of the template.
here are all the ones i know of.... Lycanthropy, Tauric, Symbiotic, Entomanothropy, and Anthropomorophic*.
*this works, but does not give you a way to figure out an unlisted animal's LA.