You can always muck with Excel using Win32::OLE (aka COM^TM) Recently I wrote the following, relatively simple, script to convert an Excel^TM file to TSV. For you I quickly swapped a few things around to convert TSV back to Excel^TM format. It worked for my simple testing. Note that the filename needs to be fully qualified or Excel^TM evilly thinks you mean it's default directory, not your current working directory.

#!perl -w
use strict;
use Win32::OLE;
use Win32::OLE::Const 'Microsoft Excel';
$Win32::OLE::Warn = 2; # Always warn with verbose error messages

# Open a new excel app, thus not stepping on anyones toes.
my $Excel = Win32::OLE->new('Excel.Application', 'Quit')
    or die "Unable to start Excel";

# Set Application Visibility 
# 0 = Not Visible    1 = Visible
$Excel->{Visible} = 0;

my $file = 'c:\test.txt'; # I tested with a TSV file.
die "'$file' not found" unless -e $file;

my $new_file = $file;
$new_file =~ s/txt$/xls/i;
if( -e $new_file )
{
    my $n = 4;
    while( --$n )
    {
        print STDERR "Deleting '$new_file' in $n seconds \r";
        sleep 1;
    }
    warn "Deleting '$new_file'                \n";
    unlink $new_file;
}

my $Book = $Excel->Workbooks->Open($file); # Open the book.
# And save it in the prefered format.
$Book->SaveAs( {
            FileName => $new_file,
            FileFormat => xlNormal,   # To save as TSV use xlText
            CreateBackup => 0} );
                
$Book->Close(0);
$Excel->Quit();
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