Here is a suggested incantation:
git clone git@github.com:emilaxelsson/imperative-edsl
git clone git@github.com:Feldspar/raw-feldspar
git clone git@github.com:kmate/zeldspar
git clone git@github.com:kmate/raw-feldspar-mcs
cd raw-feldspar-mcs
cabal sandbox init
cabal sandbox add-source ../imperative-edsl
cabal sandbox add-source ../raw-feldspar
cabal sandbox add-source ../zeldspar
cabal install --constraint="language-c-quote -full-haskell-antiquotes"