edit (August 2013): The cabal repl patches have recently been merged. This functionality will be a part of the next release.
As of this writing, there is no easy-to-use analogue to cabal-dev ghci. We plan to add a cabal repl command in the future – however, at the moment this functionality is not in Cabal HEAD.
In the meantime, you can try the following workaround:
$ cd $YOUR_PACKAGE_DIR
# For GHC >= 7.6
$ ghci -no-user-package-db -package-db .cabal-sandbox/i386-linux-ghc-7.6.1-packages.conf.d
# For GHC < 7.6
$ ghci -no-user-package-conf -package-conf .cabal-sandbox/i386-linux-ghc-7.4.2-packages.conf.d
This won’t make the modules of your package immediately available from ghci – you will have to load them with :l or import (which can break in the presence of custom preprocessors and CPP).