First, a shout-out to Les Bentley, whose wonderful Compendium of PZ2 Techniques thread contains all the information I needed to make this pose.

Since this is the Technical Forum, I'm assuming that if you're reading this far, you're familiar with editing Poser library files, and you know your way around them to some extent. Now, if we look into the pose file, there are two main sections. First, the body section:

actor BODY<br></br>
  {<br></br>
  channels<br></br>
    {<br></br>
    valueParm PBMCC_01<br></br>
      {<br></br>
      name ERCbendACNH<br></br>
      initValue 0<br></br>
      hidden 0<br></br>
      forceLimits 1<br></br>
      min -100000<br></br>
      max 100000<br></br>
      trackingScale 0.02<br></br>
      keys<br></br>
        {<br></br>
        static 0<br></br>
        k 0 0<br></br>
        }<br></br>
      interpStyleLocked 0<br></br>
      indexes 0<br></br>
      }<br></br>
... and so on with the rest of the channels.<br></br><br></br>