Are we talking about Changes or MM Harry?
If the former, I always thought that Harry would've just go to Graceland, stir the ghosts of the place up, and eat them. Graceland has a lot of spooks, IIRC. If he were to use the Ramps as the power source, he'd be too late because broken back and all that.
If the latter, MM Harry would probably still fuel his darkhallow with the ghosts of Graceland. I don't think that MM Harry is so much different from our own.
Edit: still too early for me to process things, the thread is about Changes
not gonna delete the other part of the post.