There is another syntax you can use to apply a pose to a prop in P5 and up. Poser 5 introduced a new statement "actor $CURRENT",  this applies the pose to the currently selected actor irrespective of whether it is a prop or a body part. A big advantage of using this syntax is if you have a number or instances of the same prop loaded, say box_1, box_2, box_3, you can apply the same pose file to any or all of the props.

{

version
        {
        number 6
        }

actor $CURRENT
        {
        material Preview
                {
                KdColor 0.992157 0.992157 0.992157 1 
                textureMap "GetStringRes(1029,7)"
                }
        }
}

Fore example the above MAT pose can be applied to any Poser primitive, or indeed any prop that uses 'material Preview' as its material. But remember there must still be a figure in the document before it can be applied, and this method does not work in versions before P5.