You don't need to do an 855 for this, at least not that I have ever heard of.
In Box 32, you will put the name and address of the facility, then in Box 32a, you would put the organizational NPI of the facility. You can either get that from them, or look it up on NPPES, but makes sure it is correct, or you will have issues. Nothing goes in Box 32b, unless a specific qualifier is needed by the payer...and in the case of my MAC, and other MAC's I deal with, nothing is needed there.