Anyone know how to open/use the FPK files?

[YankeePyrate]

That is the key to modding. For example, the Limited Ed. I have comes with an extra .fpk file that putting in your Custom folder cause new characters to appear in some taverns.
Anyone know where to begin? I have lots of ideas, I just need the proper tools.
I did a lot of modding in Morrowind thanks to their construction set...if only SMP came with that too!

 

[YankeePyrate]

GRRRRRRR!

So I downloaded a nice little FPK Extractor tool, but when I try to open the FPK files, it says they are all invalid...which I assume is some sort of protection setting on the file.
I MUST Crack these suckers open! <img src="http://www.piratesahoy.com/forum/style_emoticons/<#EMO_DIR#>/mybad.gif" style="vertical-align:middle" emoid="" border="0" alt="mybad.gif" /> <img src="http://www.piratesahoy.com/forum/style_emoticons/<#EMO_DIR#>/mybad.gif" style="vertical-align:middle" emoid="" border="0" alt="mybad.gif" /> <img src="http://www.piratesahoy.com/forum/style_emoticons/<#EMO_DIR#>/mad.gif" style="vertical-align:middle" emoid=":c" border="0" alt="mad.gif" />