build ghc package from repo ?

[Ranjit Jhala]

Dear ghc-users,

I'm having a rather tricky time building a fresh copy of 
ghc from the git repository (let me call it git-ghc) and 
then getting my-own-client-code to compile with the modules
from git-ghc. The catch is that my-client-code also 
depends on other cabal-installed libraries which break 
once git-ghc is installed as _the_ ghc in my system...

Is there a way I can just build git-ghc but ONLY install 
the packages (i.e. add them to the ghc-pkg database) so that 
my-own-client-code can then be compiled (by platform-ghc) 
against the modules from git-ghc?

Thanks!,

Ranjit.