[Haskell-beginners] Handling cpp and hsc2hs with Distribution.Simple

Cabal package manual says those tools are handled automatically using extensions in file names, i.e., '.hsc' for hsc2hs and '.cpphs' for haskell cpp. What should I do if I want both, i.e., I would like my file to be processed first by cpp and then by hsc2hs? Thanks, Maurício