You can use the similar threads feature for this. Its built into vBulletin.
I want to move [Similar Mod] templates to be just under first post
--------------- Added [DATE]1222747033[/DATE] at [TIME]1222747033[/TIME] ---------------
Normally similar threads [Similar Mod] appears in the bottom of the forum,
But in vbulletin.org similar threads appears below first post,
How to do this change?