Ho trovato questo esempio penso ti risolva i problemi:

<script language="javascript">
var groups2=document.isc.example.options.length
var group2=new Array(groups2)
for (i=0; i<groups2; i++)
group2[i]=new Array()
<?php
$query = "SELECT something,something_else FROM sometable WHERE somefield = '$somevalue'";
$result = mysql_query($query);
while ($row = mysql_fetch_array($result)) {
print "group2[$x][$y]=new Option(\"$row[something]\",\"$row[something_else]\");\n";
}
?>

</script>

e codice php all'interno di codce javascript