This preprint has been removed. Erik Pedersen pointed out that the main results are contained in Thm 1.40 of a preprint by G.Carlsson and E.Pedersen, "Controlled algebra and the Novikov conjecture for K- and L-theory". See Erik's homepage. I apologize. I did not look there too carefully because the applications I had in mind are rather different from those in the Carlsson-Pedersen paper.