+REP dobar covjek, great player and leader.

-rep sojka iz kruga dvojke

Once you've done that, of course you'll also have to add the hak pack to your module. Back up your module first just to be safe.

You need to use the hak tool found in your NWN utilities folder to create a hak that has the portraits. I think it has to be in .tga format, and has to be in several sizes with specific names for each size. Then you need to create a copy of portraits.2da (if you don't have a 2dasource folder, I think you should have a 2dasource.zip that contains all of them). Add your new portraits to this file, which is essentially a space-delimited spreadsheet that the engine uses to determine which resources to load. This modified 2da will also go in the hak pack.
Check here for an example of how it can be done:
http://nwvault.ign.com/View.php?view=Hakpaks.Detail&id=7399
You can open up this hak with the hak editor. But don't use their 2da as a base, it's based on CEP so it'll have all sorts of extra entries you don't want.
http://nwn.wikia.com/wiki/Portrait
Here's a little more info about portraits, but don't follow their bit about the override folder.

You're never online when I am, bruv

I'm online all the time, but only available some of the time