On a RHEL4 U2 system, you have to do this to help the configure and make scripts
ln -s /usr/X11R6/lib64/libX11.so.6 /usr/X11R6/lib64/libX11.a
I configured it with this
./configure --with-x --x-libraries=/usr/X11R6/lib64/ COMPILED_BY="matt walsh"
-- MattWalsh - 05 May 2006