Err.. From what I remember of the models, they don't have any animations( in fact, they can't), the texture sheets are blurry and the model is certainly not crisp.
In any case, you can't use it as a base model, as you can't modify complied mdl files.
It would be very easy to make them again in gmax if you really wanted - especially the UFO, which is nothing more than a few spheres and torus shapes. The shuttle, likewise, is available as freeware with a much better model.
I really don't understand why you'd want to do this.
I fly through the valley of death, but I fear no evil,for I am at 80,000 feet and climbing. Let's powerdive and scare that poor soul in that Ultralight there.