I'm glad I found this thread. I'm thinking about growing hops this year and wanted to know the flowering response in hops.
Just to add in my 2 cents, I'm a researcher and I work on the genetics and molecular biology of the photoperiodic flowering responses in the model plant Arabidopsis. Controlling the flowering response shouldn't be hard but you'll need lights and a dark shed or something like that to strictly control the light cycle. Once they've been induced to flower, the process is largely irreversible so you can put them back outside / in the greenhouse or what have you. If they need vernalization then usually 3-4 weeks from what I've read is enough to induce competency, but that might mean you need a cold room or something depending on plant size.
I might try this on cuttings I got from a friend's plant this summer, so I'll try to keep the thread updated.