Run the 68k W3D version of GLQuake (preferably Soft3Dev version) first and let it extract all the files into ID1 folders (this happens by default when you run the game). Exit the game. Move the ID1 folders (which should now contain the extracted files as well) to the folder which contains BlitzQuakeWOS or preferably GLQuakeWOS and try running the PPC version then (after setting appropriate stack size, of course).
I've never successfully ran BlitzQuakeWOS, but I've managed to make GLQuakeWOS (the Soft3Dev version) by using the above mentioned trick.
