301 htaccess redirect: add segment to old URL's

Question

I'm trying to make sure old url's aren't broken after the site's URL structure has changed from this:

• http://www.domain.com/section/entry_name

to this:

• http://www.domain.com/section/event_name/entry_name

But to make it a bit more complex, I'm using the segments to sort entries, for example:

• http://www.domain.com/news/amazing_event/date/asc
• http://www.domain.com/videos/my_event/title/desc

The new structure only effects one particular event (amazing_event) and should leave the other URL's alone. Where do I even begin to tackle this?

My current .htaccess looks like:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /index.php/$1 [L]

Thanks - appreciate any tips.