I'm not sure what data you want to extract. Puppet pin keyframe data looks like this:

Adobe After Effects 8.0 Keyframe Data

          Units Per Second          29.97
          Source Width          318
          Source Height          52
          Source Pixel Aspect Ratio          1
          Comp Pixel Aspect Ratio          1

Effects          Puppet #7          arap #3          Mesh          Mesh #1          Deform          Pin #2          Position
          Frame          X pixels          Y pixels 
          51          289.175          21 
          59          289.063          17 
          64          287.032          1 
          66          287.023          -3 
          70          287.018          -7 
          74          287.009          45 
          82          287.001          59 
          83          287.001          57 
          84          283.002          49 
          88          283.001          17 
          90          277.001          -1 
          96          277          -5 
          101          279          25 
          103          279          39 
          110          279          43 
          118          269          -86.6667 
          121          269          -266 
          122          271          -256 
          129          273          -236

End of Keyframe Data

This is all yoy get when you copy the keyframes. Since this is a scripting question, I'd move the post to the that forum. You'll find it on the AE Forum home page in the right column.

What are you trying to do with the data?

I agree with Rick. You're betting on the wrong horse if you hope to export this kind of stuff from AE. If you need UV texturing on a mesh, then use a mesh in a 3D program and export it. Due to how the Puppet Mesh is generated, the distorsioss will be quite uneven, anyway and only get worse at lower (texture) resolutions, nothing what I would like to see in a game....

Mylenium