Can't select qmake executable on system's path (/usr/bin/) on Qt Preferences

When installing the package "Qt Library 4.7.4" (distributed separately) on a MAC OS X Lion 10.7 all Qt executables are saved in the hidden system path /usr/bin, this version of Qt did NOT get detected automatically on Qt Creator. If one tries to add the newly installed version through the App "Preferences" one will find the /usr/bin/qmake file greyed out and unselectable.

I suspect this is because that file is an alias of qmake-4.7 which can't be selected either.