ok, first things first, you know that the pk3 is a zip file right so open it with winzip or hop to my site and download pakscape which will let you open it without changing the ending
pak0.pk3 is the main file that hase most of the things in it, this is where to get the models and textures etc.
once inside the pk3 file look for a subfolder called models
browse around there
drag the media you want out into a seperate folder, don't unzip the whole pk3 it's over 500mb.
if you have dbp it can load the .md3 files (the models) anyway, i don't know about dbc.
lithunwrap (lithium unwrap) can convert these to .x, .3ds, .cob (for truespace) and a few other formats
http://www.larinar.tk
AMD athlon thoroughbred 2200, 512Mb ram, 40Gb HD, ati saphire radeon 9600 atlantis w/128mb ddr ram, good creative-labs soundcard, cd-rw + dvd drives.