So you'd like to build Firefox 1.5 from source so that it's even leaner and meaner? Let me show you the way young padawan...
$ sed -i "s/ enum/& xptinfo_enum_1/" xpcom/reflect/xptinfo/public/xptinfo.h
$ make -f client.mk build
# make -f client.mk install
# install -v -m755 -d /usr/lib/firefox-1.5/chrome/icons/default
# ln -v -n -f -s ../../../icons/default.xpm \
> /usr/lib/firefox-1.5/chrome/icons/default
# install -v -m755 -d /usr/include/firefox-1.5/nss
# cp -v -Lf ../firefox-build/dist/{private,public}/nss/*.h \
> /usr/include/firefox-1.5/nss
# chown -v -R root:root \
> /usr/lib/firefox-1.5/extensions/inspector@mozilla.org/*
That should be it. You should be all set.