They'll give you a list of things that have to be removed from the premises before they'd do it. They'll be interested, training is always a good thing, and a real house to use is great.
I worked for a plumbing company once, and the owner had a house he was going to let the FD burn. He sent a couple of us out there to strip the shingles off the roof, and I don't remember what else had to be cleared first.
Call/visit the local department, they'll tell what ya need to know, and most likely they'll apprciate your wanting to donate a house for training.
I was also with a volunteer department once upon a time, and I can recall to instances where people donated a house and a trailer for us to burn for training. The chief and training officer were very happy.