xmkmf 
make Makefiles 
make 'CC=gcc -arch ppc -arch i386 -iwithsysroot /Developer/SDKs/MacOSX10.4u.sdk -isysroot /Developer/SDKs/MacOSX10.4u.sdk -mmacosx-version-min=10.4 -I/Developer/SDKs/MacOSX10.4u.sdk/usr/X11R6/include -L/Developer/SDKs/MacOSX10.4u.sdk/usr/X11R6/lib' INCROOT=/usr/X11R6/include USRLIBDIR=/usr/X11R6/lib SHLIBDIR=/usr/X11R6/lib MANPATH=/usr/X11R6/man PROJECTROOT=/usr/X11R6 BINDIR=/usr/X11R6/bin LIBDIR=/usr/X11R6/lib/X11 SHAREDIR=/usr/X11R6/share/X11 LIBEXECDIR=/usr/X11R6/libexec