Is there a way to bypass the dependency install step of rosinstall? 

After reformatting my hard drive, I am trying to reinstall ros on OSX.  This time around, I am especially keen to minimize my port installs and python versions. I prefer to use easy_install with the system python instead, wherever possible. 

Unfortunately rosinstall wants to install lots of ports, even though I have the relevant python packages (pyyaml and paramiko) already installed. 

--Nick