Change a Permalink URL to match a deleted Permalink

I recently posted an Article, but I made a mistake. First I posted it as private then I deleted the post. The link to the url for the deleted post ended up in a WebSphere RSS Feed at:

http://feeds.technorati.com/feed/posts/tag/websphere

The problem is that I deleted the article then reposted it. Now the post is under a new permalink , but the feed has the old permalink. My blog is WordPress based. I tried to change the post slug to match the url in the feed, but it won’t allow me to use the URL that is in the feed.

Here is the bad URL in the feed:

http://blog.peningo.com/2007/08/02/peningo-systems-selected-to-provide-websphere-commerce-development-and-support-consulting-services/

and here is the good URL

http://blog.peningo.com/2007/08/02/peningo-systems-selected-to-provide-websphere-commerce-development-and-support-consulting-services-2/

How can change the existing permalink to match the deleted permalink that was picked up in the feeds?

Thanks

Ed
Peningo Systems