Something

Aiur bin # cat et.old
#!/bin/sh
cd "/opt/enemy-territory"
if [ -n "/opt/enemy-territory" ] ; then
        if [ "${LD_LIBRARY_PATH+set}" = "set" ] ; then
                export LD_LIBRARY_PATH="${LD_LIBRARY_PATH}:/opt/enemy-territory"
                export LD_PRELOAD="et-sdl-sound.so"
        else
                export LD_LIBRARY_PATH="/opt/enemy-territory"
        fi
fi
exec ./et.x86 "$@"
unset LD_PRELOAD