I use the free utility "Poser Compressor 1.1" (PoserCom.exe) from Dimension3D, you can find a link here in the Dimension3D Free Stuff.

Whilst it won't decompress the crz and obz at the same time (unless you use it to decompress the whole Runtime), at least you don't need to start Poser to use it. It also accepts Drag & Drop. I find it very useful.