Dynamically 301 Redirect 404 Page Not Found In ASP.NET

I have been building our new content management system, and I knew that our first site to be using it would need have a lot of pages 301 redirected as we are going to change the file structure and pages names (And the old site has has a lot of SEO done). So I thought it would be a great ‘Admin Tool’ to be able to add the old and new pages into a table and if a 404 was served (One of the old pages) check against the pages in the database and 301 redirect the page to the new one.