place the pk3 file in your ID1 folder and you need the darkplaces engine that can be found here [link]
made using blender + zbrush3.5r3 this image is rendered using the marmoset toolbag (could not get a good screenshot while it tried to kill me in game )
(edit) ops had the wrong file selected so it would not go for the pk3 file on the download button
just tried it myself with a fresh install of darkplaces and it worked just fine. here is what i did first got myself the darkplaces engine with the "DarkPlaces engine Windows/Linux/Mac OpenGL build 20110628 " link unpacked that into a my quake folder with only the id1 folder with its pak0.pak and pak1.pak files then unpacked my model to quake\ID1\progs started the darkplaces.exe and went to the final level. not sure what it could be if that won't work. one thing to note however you need to set the lighting to the highest setting or its going to look all flat.
cause using this with vanilla quake should not work at all.
here is what i did first got myself the darkplaces engine with the "DarkPlaces engine Windows/Linux/Mac OpenGL build 20110628 " link unpacked that into a my quake folder with only the id1 folder with its pak0.pak and pak1.pak files then unpacked my model to quake\ID1\progs
started the darkplaces.exe and went to the final level. not sure what it could be if that won't work.
one thing to note however you need to set the lighting to the highest setting or its going to look all flat.