I guess the best training is experience (I know, maybe not the answer you are looking for). If you hire someone and closely check up on how that person is doing in your company, you can get some feeling about what technical and personal traits are really needed.

I don't know about formal training, I can only imagine that something exists. But what also works is to get the company's recruiter more involved. Short of formal training, they can be a coach for those involved in the hiring process.