Which Hook Location to Hide Forum???

[AsscBB]

I hope someone has an idea that may be able to help.

I'm trying to set up an alternate conditional structure to hide forums/subforums based on forumid, and other information. I have the conditional set up which will drive wether to show or hide, but where I'm stuck is:
*the proper command to use to change the permission on the fly
*which hook location(s) to either place or call the function

To give an example, lets say I have a true/false variable (at least this part works) I intend to use as a switch to show/hide a forumid , what command does my function need to call to allow/deny the user the ability to see/post/etc a forum/thread/post and which hook(s) should I use to place and call the function?

I've tried solving this problem with usergroups and permissions, but my application does not play well with that solution.

Thanks!

Scott