I have no pics, but I do have an observation. While I have not extensively studied photos of scrappings, the few that I have seen suggest that the cutting job didn't start at the bottom. I see layout representations of the job showing a boiler left on the ground, but the photos I have seen show the boiler being cut up on the frame/wheels.
I make no claim to "THIS is how it was done," but my observations suggest it.
I would love to see photos of the actual job which match or refute my observation!