sandboxer is a wrapper around cabal-dev that overrides the default
sandbox location with one of your choice. This way, multiple projects
can share the same sandbox, even if your development/build environment
doesn't provide options for specifying the cabal-dev sandbox.
Put source path/to/sandboxer.sh somewhere in your shell init
script. Note that you must source it, since it works by defining
functions. Executing it directly will not be useful, which is why it's
mode 0644.
sandboxer init name creates a new sandbox. sandboxer activate name
activates that sandbox, and sandboxer deactivate deactivates the
current sandbox. Sandboxes are created in ~/.sandboxer by default, but
you can set $SANDBOXER_ROOT to override this.
sandboxer also sets $GHC_PACKAGE_PATH to help with applications
that call runghc directly; if this isn't what you want you can just
comment it out (and let me know so I can add an option!).