Hey VikesRule,
I hope you mean Minnesota Vikings, but even if you meant the old Vikings of centuries gone by they were cool to. Vikings are my fav NFL team.
Anyways the system is set up to make additional post icon categories located in your Admin CP > Post Icon Manager
Even if you make "X" amount of categories only the top category or display order 1 will appear open. Meaning on my forum when I added the one's that I did, it looks like this:
http://img.photobucket.com/albums/v3...n_666/PIex.png
Notice only the top set of Post Icons are open?
That's because it's designed to only have the top one be open. I found this out by going into another forum where we've restricted one set of post icons to one forum only. If anything, restricting Post Icons to a certain forum is a modification here, if you'd like that let me know and I'll try to dig it up.
Otherwise everything you need is naturally in the Admin CP to add more post icons. As far as the images themselves, there are no template or php file changes you need to make, you can upload whatever images you want. I just used large png's because more and more people use bigger monitors these days including myself.
If I've not answered your question, please clarify further what I can help you with.
peace,
loa