cabal packaging and --libdir

I think a --libdir option is needed in Cabal to help packagers that need to specific where libraries are installed. For example Fedora Core x86_64 (amd64) arch 64bit libs should be installed under $prefix/lib64, whereas cabal assumes $prefix/lib. Could a --libdir please be added or is there another way? Jens -- Fedora Haskell packages http://haskell.org/fedora