my $db_file   = 'd:\path\to\database.mdb';
my $db_user   = 'username';
my $db_passwd = 'pasword';

my $dbh = DBI->connect(
   'dbi:ADO:Provider=Microsoft.Jet.OLEDB.4.0;Data Source='.$db_file,
   $db_user,
   $db_passwd
) or die $DBI::errstr;
...