Can't you just do this in the template? I have had the buttons linking to 'make new post', but surely if you link it to:
http://yourforum/showthread.php?s=&g...ost&forumid=xx
Just replacing the forum id with the forum id call $.
I'm also not sure why you need this when there's a link next to the name in the 'last post' column which does the same thing? Bit confused.