use Net::SFTP::Foreign;
my $sftp = Net::SFTP::Foreign->new(
			host => 'delivery.myserver.com', 
			port => '22',
			backend => 'Net_SSH2',
			user => 'ftp_user',  
			more => [qw(-i mytransaction.private.key.ppk)],
			ssh_cmd => 'plink');
$sftp->die_on_error("Unable to establish SFTP connection");