Mod Rewrite/htaccess help

I have been working on a solution to get rid of the ? in a script for awhile and have finally had someone tell me how I could use mod rewrite to do it. The problem is it involves using the httpd.conf file and a directory on the root of the server. Neither of which I have access to since I'm not on a dedicated server. Can someone tell me how to translate the following code over to a .htaccess file so that I can use it?

Thanks

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Here's a quick fix to get nice urls
(http://www.yourname.dom/cat1/subcat2/subcat3/...)
for Apache users:
- Make sure you got mod_rewrite installed
- Add this to your httpd.conf for a top category
cat1 called 'opendir':

RewriteEngine On
RewriteRule ^/opendir/(.+) /yourpath/cgi-bin/odp/main.cgi?/$1 [T=application/x-httpd-cgi,L]
RewriteRule ^/opendir /yourpath/cgi-bin/odp/main.cgi [T=application/x-httpd-cgi]

- Replace '$cgiurl/main.cgi' and '$cgiurl/main.cgi'
in all files with 'opendir'
- Restart Apache.

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