bootstrapping

As a newbie to the cabal-devel list, I don't know whether this question has already been thought about much, and perhaps even has a really good answer. I notice that the Cabal darcs repo now has a Cabal.cabal file that uses configurations. Presumably this is self-bootstrapping. But is it still possible to upgrade an older version of Cabal (e.g. supplied with ghc-6.2) to the latest version, using only the older version of Cabal itself? Regards, Malcolm