Display Showthread starting at a specific post

[tfw2005]

Hoping someone can point in the right direction:

Is it possible, default or with a plugin, to call showthread.php starting at a specific post. So that when you load the page, the first post is the postid you referenced in the url. Something with the logic of:

[pre]http://www.site.com/forum/showthread.php?t=12345&post_from=456789[/pre]

This is different than showthread.php?p=456789 - doing that brings you to the page that post is on, but if it's the 5th post on the page, loads the 4 before it and shoots you down to an anchor.

Any help appreciated. Thanks!