Try doing a manual install, post the data in the SQL/mysql.initial.sql into you database. If you haven't setup your config go to your config folder and make a copy of the main.inc.php.dist and db.inc.php.dist then rename the copy's to main.inc.php and db.inc.php. Open the db.inc.php file and change the $rcmail_config['db_dsnw'] line to
$rcmail_config['db_dsnw'] = 'mysql://db_username:db_password@localhost/database';
Now open the main.inc.php file and edit the following line:
$rcmail_config['default_host'] = '';
Enter your mail server
That should give a basic install, let me know if you have any more problems.