I've used the Developed Shapes product with CATIA V5 in the past to get the approximate flat pattern. The result was not 100% accurate, but it was close enough to get me started. Based on the "K" factor of the material, start with offsetting the original surface to get the "Neutral Axis" surface.
CATIA V6 might have similar capabilities in the newer SheetMetal product. Check with your CATIA reseller.