[Haskell-cafe] Vi mode in ghci?

Somehow in the distant past I managed to get vi editing mode working for ghci on ghc 6, but when I upgraded to ghc 7, I can't seem to figure out how to enable it anymore. I think I might have been using ghci-haskeline in the past. A post I read somewhere suggested that ghc 7 should have innate support for vi mode, but I can't figure out if it does, or how to enable it. Does anyone know? I'm willing to recompile ghc to use readline to get vi mode support if that is possible and the only way to do so.