It is possible to method to discover if your server supports mod_rewrite &lifier .htcaccess

http://us3.php.net/apache_get_modules will output something such as the next:

Array

(

    [] => core

    [1] => http_core

    [2] => mod_so

    [3] => sapi_apache2

    [4] => mod_mime

    [5] => mod_rewrite

)

Just search for mod_rewrite. You can even write a little function using in_array() to really make it simpler to find out whether confirmed module is loaded or otherwise.

I'd produce a test scenario with the addition of mod_rewrite to .htaccess. There's a good example here.