happyjapm64, although I think it's a cool idea I'm not sure if this bipack method will work.
First, how do you intend to match the speeds of the two films? Is there an ortho film that is slow enough and a IR film that is fast enough to make for the same exposure times w/ this bipack? The IR has to go thru the ortho film and a red filter, meanwhile the ortho film is right on top w/ no filtration.
And also, since the ortho would be, as you said, a record of the green & blue, it's not a true color separation by any means. Same goes for the IR layer which thru only a red filter won't be 100% IR.
So false color it surely will be, but Color EIR it certainly can't resemble (why am I talking like Yoda?). That being said though, it could still be very interesting.
The best method would be a one-shot camera (not practical... prohibitively expensive IMO) or just using filters and taking three individual shots. However, I do like the idea of bi/tri-packing it, but the particulars need to be ironed out.