I haven't used it, but I'm working on setting up an exposure system so I can.
I've only seen the film on eBay. Dry Film Solder Mask Roll of 12 in x 42.5 in (bigger lenght by request)
I think you'd have to photo etch it, but you could do that by just printing your mask on velum or transparency film. From what I understand it's a 2 step cure. The first exposure just cures it enough that you can wash away the resist on your pads, and the second cure kind of bakes it on.
It would certainly hold up to reflow temperatures. Making a mask to apply solder paste for SMD components is probably the more challenging part.