[BirdOPrey5]

Step 1. Make 4 icons per forum. call them:
CUSTOM_forum_new.gif
CUSTOM_forum_old.gif
CUSTOM_forum_new_lock.gif
CUSTOM_forum_old_lock.gif
(new is the version when there are new posts and the forum is open, old is when there are no new posts and the forum is open. new_lock is when there are new posts but the user can't post in that forum (it's locked.) old_lock is when there are no new posts and it's locked.

Step 2. Upload Files
Upload all images to your images/statusicon directory via FTP.

Step 3. Go to Admin CP -> Forum Manager
Edit the forum you want to make the custom icons for, find the box Prefix for Forum Status Images and put: CUSTOM_ in the box.

Now save and you should see the forum icons when you view the forum index.

Change "CUSTOM_" in the file names and the box in step 3 to whatever you want, usually a word that describes the forum you are making the icons for.