use warnings;
use strict;
use Win32::OLE ();
use Win32::OLE::Const 'Microsoft Excel';
$Win32::OLE::Warn = 3;  # die on errors

my $Excel = Win32::OLE->new('Excel.Application', 'Quit') or die "Failed to open Excel";
# or to get running Excel instance: Win32::OLE->GetActiveObject('Excel.Application')

my $const = Win32::OLE::Const->Load('Microsoft Office '.$Excel->{Version}.' Object Library');
$Excel->{AutomationSecurity} = $const->{msoAutomationSecurityForceDisable};

$Excel->{Visible} = 1;
my $Book = $Excel->Workbooks->Open("filename.xlsm");
$Book->Activate;
# ...
$Excel->Quit;