Thaks for your help. The following worked for me: Note this is only the relevant part of the code.

use Tk::ItemStyle;        # use itemstyle

# define the simple styles
my $rj = $hlist->ItemStyle("text", -justify => 'right');
my $cj = $hlist->ItemStyle("text", -justify => 'center');

# when calling itemCreate use a style
$hlist->itemCreate($job, $option++, -text => $cpu{$job}, -itemtype => 
+'text', -style => $rj);
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