How I install (if it helps someone)
in Ubuntu Hardy:
1. Install libqt4-dev
2. Install libgtk2.0-dev
3. Install svn
4. svn co svn://labs.trolltech.com/svn/styles/gtkstyle
5. qmake && make
6. sudo make install
then select gtk theme in qt4-qtconfig (you must install it too)