[Logician]

First install Advanced Templates Hack, then edit template newthread and add this code in the begining (before everything else!):

PHP Code:

[[($bbuserinfo[posts]<X and $forumid==Y)]]
You dont have permission to write here because you have less than X posts (You can use all HTML codes you want to design the error page nicely here)
[[/($bbuserinfo[posts]<X and $forumid==Y)]][[(!($bbuserinfo[posts]<X and $forumid==Y))]] 


Now go to the end of template and (after everything) add this

PHP Code:

[[/(!($bbuserinfo[posts]<X and $forumid==Y))]] 


Replace all Xs with min.post count to post in this forum and Y with your forumid. Please apply carefully and correctly and after you applied it, test your new template with different conditions (with a user less than X posts, user more than x posts, in forum Y, outside forum Y etc) to make sure you applied it correctly..

Enjoy..