I downloaded the M1Abrams tank from that site and tried it. Try this, Look through all the lwo parts until you find a file named something.lws In my case it was m1abrams.lws. From bryce import this file. It will call all the other pieces and materials for the other 80+ lwo parts. As soon as it loads, group the whole thing. I had to scale the abrams from 100 X,Y,Z to about 3 because it came into bryce huge for some reason. Press the down arrow to drop this to the ground plane.