X11 and Open Motif libraries

I'm trying to install a quite old Fortran code requiring xorg and OpenMotif libraries.

Here is part of the install script where the code is checking for these libraries:

    echo -n "Esistono le librerie X11 ? ... "
    (find /usr -name lost+found -prune -name audit -prune -o -name libX11.so > /tmp/___) >& /dev/null
    set trovato=(`cat /tmp/___`)
    rm -f /tmp/___
    if( $#trovato < 1 ) then
    (find /usr -name lost+found -prune -name audit -prune -o -name 'libX11.so*' > /tmp/___) >& /dev/null
    set trovate=(`cat /tmp/___`)
    rm -f /tmp/___
    if( $#trovate < 1 ) then
    echo "ASSURDO! Non appare installato in modo corretto"
    echo "nemmeno il server X11: ERRORE CRITICISSIMO"
    echo "(sei sicuro/a di essere in inittab 5 ?)"
    else
    echo "Appare mancante la libreria  libX11.so  e tuttavia esistono "
    echo "librerie libX11.so.n.m. Eseguire (come root) un link simbolico "
    echo "della libreria opportuna a  libX11.so  e ripetere l'esecuzione "
    echo "del presente script."
    endif
    exit
    endif
    echo  "Trovate "
    echo -n "Esistono le librerie dell'Intrinsic Toolkit ? ... "
    (find /usr -name lost+found -prune -name audit -prune -o -name libXt.so > /tmp/___) >& /dev/null
    set trovato=(`cat /tmp/___`)
    rm -f cat /tmp/___
    if( $#trovato < 1 ) then
    (find /usr -name lost+found -prune -name audit -prune -o -name 'libXt.so*' > /tmp/___) >& /dev/null
    set trovate=(`cat /tmp/___`)
    rm -f cat /tmp/___
    if( $#trovate < 1 ) then
    echo " "
    echo " "
    echo "ASSURDO! Non appare installato in modo corretto"
    echo "nemmeno il server X11: ERRORE CRITICISSIMO"
    echo "(sei sicuro/a di essere in inittab 5 ?)"
    else
    echo "Appare mancante la libreria  libXt.so  e tuttavia esistono "
    echo "librerie libXt.so.n.m. Eseguire (come root) un link simbolico "
    echo "della libreria opportuna a  libXt.so  e ripetere l'esecuzione "
    echo "del presente script."
    endif
    exit
    endif
    echo  "Trovate "
    echo -n "Esistono le librerie di OpenMotif ? ... "
    set MOTIFLIB=""
    (find /usr -name lost+found -prune -name audit -prune -o -name libXm.so > /tmp/___) >& /dev/null
    set trovato=(`cat /tmp/___`)
    rm -f /tmp/___
    if( $#trovato < 1 ) then
    (find /usr -name lost+found -prune -name audit -prune -o -name 'libXm.so*' > /tmp/___) >& /dev/null
    set trovate=(`cat /tmp/___`)
    rm -f /tmp/___
    if( $#trovate < 1 ) then
    echo "No. "
    echo " "
    echo "Non appaiono installate in modo corretto le librerie di OpenMotif:"
    echo " ERRORE CRITICISSIMO: giotto NON FUNZIONA SENZA DI LORO"
    else
    echo "Appare mancante la libreria  libXm.so  e tuttavia esistono "
    echo "librerie libXm.so.n.m. Eseguire (come root) un link simbolico "
    echo "della libreria opportuna a  libXm.so  e ripetere l'esecuzione "
    echo "del presente script."
    endif
    exit
    else
    echo  "Trovate "
    set MOTIFLIB=`dirname $trovato[1]`
    endif
    if($MOTIFLIB == "") exit
    set MOTIFLIB=( -L $MOTIFLIB )

Ok, I know this is in Italian, and I can't even translate it properly as I speak French…

But I hope I can give an idea about the libraries dependencies.

My question is : I'm running Snow Leopard with XCode 4 installed. I have the X11 installed too.

Are the X11 libraries present ? Am I able to provide these libraries without additional installation ?

I'm even more confused about OpenMotif, so any help or suggestion to install (or find) these are welcome.