There is a great new Emacs plugin from Eric Merritt that like FlyMake builds your code and highlights within Emacs any errors or warnings, but unlike FlyMake builds across the whole project. You can clone the mode from here projmake-mode
After cloning the repo to your desired location add this bit to your dot emacs file, replacing <PATH> with the path to where you cloned the repo.
[gist]3794732[/gist]
This Emacs code also uses add-hook to set projmake-mode to start for erlang-mode is loaded. ...