change the timestamp of a post without it affecting the URL / $10

I’d really appreciate it if anyone could tell me how to do the following, i’ve even created a mahalo answers question for $10:

http://www.mahalo.com/answers/wordpress/how-to-change-the-timestamp-of-wordpress-post-without-it-affecting-the-url-of-the-story

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we are using 2.7

write and publish a story now, which would create this URL (we already use this permalink structure)

domain.com/2009-03-07/story-title

and then next Wednesday (say 3.11.09) I would like to change the publishing/timestamp to 3.11.09 so that the story goes back to the top of front page of the blog, and start cycling through the loop again but without it changing the URL of the post.

I would like to be able to do this without editing the database, so that writers can do it easily with technical knowledge.