codeigniter htaccess exception for a specific folder

[eluser]WarDoGG[/eluser]
Below is my htaccess file for codeigniter setup , which converts a/b to index.php/a/b However, I want to add an exception that if a=cometchat then, it will not do the rewrite.

Please help

Code:

<IfModule mod_rewrite.c>

  # Make sure directory listing is disabled
    Options +FollowSymLinks -Indexes
    RewriteEngine on

    # Keep people out of codeigniter directory and Git/Mercurial data
    RedirectMatch 403 ^/(system|\.git|\.hg).*$

    # Send request via index.php (again, not if its a real file or folder)
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d

    <IfModule mod_php5.c>
        RewriteRule ^(.*)$ index.php/$1 [L]
    </IfModule>

    <IfModule !mod_php5.c>
        RewriteRule ^(.*)$ index.php?/$1 [L]
    </IfModule>

</IfModule>