C++:
_http://www.eclipse.org/cdt/
_http://www.eclipse.org/downloads/download.php?file=/tools/cdt/releases/ganymede/dist/cdt-master-5.0.0.zip

Qt4:
Ручками - _http://scroogie.de/index.php?/archives/61-Qt4-in-Eclipse.html
Плагин - _http://trolltech.com/developer/downloads/qt/eclipse-integration-download