To address the broader question "How do Poses really work?". A pose file is a means of injecting data into an element (for want of a better word) in a Poser document. Standard poses, the ones saved from the Poser 4 interface, save "k" ("keys" line) values for rotation, translation, and morph (targetGeom) channels, essentially these are the values that appear above a dial in the Paramiters Pallet. Pose files are plain text files (but in P5 they may be compressed), they can be edited in a text editor (I use EditPad Lite, or a cr2 editor (e.g. CR2Builder). Here is a snippet from a pose file:

actor hip:1
        {
        channels
                {
                rotateY yrot
                        {
                        keys
                                {
                                k  0  -6.5
                                }
                        }

The first line defines the actor (body part) that the pose applies to, the colon/number ":1" is optional. The third line defines the "channels" block. The fith line "rotateY yrot" is a channel type (what the channel does) "rotateY", plus the internal name of the channel "yrot". The seventh line difines the start of the "keys" (frame #'s and paramiter values). The nineth "k" line is the real meat in this example, all that the previous lins do is to point to the location of this line within the figure (or prop, or whatever). The "k" line contains two numbers, the first is the frame number, in a static pose this will always be "0", in an animation pose there may be many "frame numbers, each refering to a diffrent frame in the animation. The second number "-6.5" is the paramiter value, it says "set this dial to minus six point five", it is this number that does the actual posing. Note that each opening brace "{" within the file must have a corrisponding closing brace "}", miss matched braces are a common cause of problems in Poser files. In the above example the pose file injects a value for a rotation channel, however pose files can be constructed (in a text editor) to inject many other things, scaling, material settings, morph targets (deltas), and a whole hoste of others. One thing that a pose file can not inject is a new channel, a pose file can only inject data into a channel that already exists.