Ci sono riuscito, ecco il codice:


<ul class="menu" id="menu">
<li>
<li><a href="#" class="menulink">Italia</a>
<ul>
<li id="a1"><a href="#" class="sub topline" onclick="document.getElementById('choice').value=t his.innerHTML">Nord</a>
<ul>
<li id="b1" class="sub2 topline"><a href="#" onclick="document.getElementById('choice').value=d ocument.getElementById('a1').childNodes[0].innerHTML+' / '+this.innerHTML">Lombardia</a>
<ul>
<li><a href="#" class="topline" onclick="document.getElementById('choice').value=d ocument.getElementById('a1').childNodes[0].innerHTML+' / '+document.getElementById('b1').childNodes[0].innerHTML+' / '+this.innerHTML">Milano</a></li>
<li><a href="#" onclick="document.getElementById('choice').value=d ocument.getElementById('a1').childNodes[0].innerHTML+' / '+document.getElementById('b1').childNodes[0].innerHTML+' / '+this.innerHTML">Bergamo</a></li>
<li><a href="#" onclick="document.getElementById('choice').value=d ocument.getElementById('a1').childNodes[0].innerHTML+' / '+document.getElementById('b1').childNodes[0].innerHTML+' / '+this.innerHTML">Pavia</a></li>
</ul>
</li>
<li id="b2"><a href="#" class="sub2" onclick="document.getElementById('choice').value=d ocument.getElementById('a1').childNodes[0].innerHTML+' / '+this.innerHTML">Piemonte</a>
<ul>
<li><a href="#" class="topline" onclick="document.getElementById('choice').value=d ocument.getElementById('a1').childNodes[0].innerHTML+' / '+document.getElementById('b2').childNodes[0].innerHTML+' / '+this.innerHTML">Torino</a></li>
<li><a href="#" onclick="document.getElementById('choice').value=d ocument.getElementById('a1').childNodes[0].innerHTML+' / '+document.getElementById('b2').childNodes[0].innerHTML+' / '+this.innerHTML">Alessandria</a></li>
</ul>
</li>
</ul>
</li>
<li id="a2"><a href="#" onclick="document.getElementById('choice').value=t his.innerHTML">Centro</a></li>
<li id="a3"><a href="#" onclick="document.getElementById('choice').value=t his.innerHTML">Sud</a></li>
</ul>
</li>
</ul>


Grazie mille, di cuore Vindav, per i preziosi consigli !!!

Se il codice postato lo si puo' migliorare, accolgo volentieri suggerimenti