my $newtext0 = 'foobar0';  #get from a popup dialog or wherever
my $newtext1 = 'foobar1';
my $newtext2 = 'foobar2';

$hlist->selectionSet($s);

$hlist->itemConfigure($s, 0,  -text=> $newtext0 ); #column 0
$hlist->itemConfigure($s, 1,  -text=> $newtext1 ); #column 1
$hlist->itemConfigure($s, 2,  -text=> $newtext2 ); #column 2