open foo.xml ;
set /Listens/Listen/param[@name="SSLKeyStorePassword"]/@value 'BLABLA8' ;
save :b ;

##</code><code>##

my $l = /Listens/Listen/param[@name="SSLKeyStorePassword"] ;
if (count($l) > 1) echo :e 'More than one node found' ;
set $l/@value 'BLABLA8' ;