Hmm, FWIW, the lyx binary with debug information disabled doesn't segfault at all.
You can git clone git://git.lyx.org/lyx
to get the current sources. You will also need to apply autotools patch and app crash on mouse click patch.
Assuming you have libqt4 revision 4 installed:
./autogen.sh
./configure --prefix=/tmp/lyx --without-included-boost
make -jN
make install
/tmp/lyx/bin/lyx
Without latest libqt4 package, you'll need to specify QT_CORE_CFLAGS and QT_FRONTEND_CFLAGS with paths to headers/x86/(QtCore|QtGui).