#!/usr/bin/perl -w
use strict;
use Win32::OLE qw|EVENTS|;

my $excel = Win32::OLE->CreateObject("Excel.Application",'Quit');
Win32::OLE->WithEvents($excel,\&Event);
$excel->{Visible} = 1;
#...etc...
Win32::OLE->MessageLoop();

sub Event {
    my ($obj, $event,@params) = @_;
    print "Event triggered: '$event'\n";
}

1;