Richard (and PKM), the rollfilm is *very* curly, it takes quite some force to hold it flat- I am guessing that adhesive film won't do it. I tried various rather strong tapes etc. and nothing could hold the film firmly enough.... without also leaving gummy residue behind. What I suppose one might do is cut the film into strips and press it for some time to try to relieve some of the curl. But really, I tried stapling film fragments onto transparency stock and that works fine. Holds the film quite flat, really.
About contact printing to 8x10, this would be a good way to get the rollfilm sprocket effect, but then again, the only reason I was thinking about this was because the particular rollfilms that interested me are/were not available in LF... HIE, scala, digibase etc. PKM's motives may be different, of course.
Another thought would be to get a thin sheet of glass and shove the film underneath that.
Definitely explore this further and let us know how it works out!