I cannot troubleshoot this for you since I don't have Acrobat 9 but you can look through this document to see if you will find anything:
Answered in your other thread - it's not possible.
Not possible with Acrobat via scripting, but for Acrobat 9 Extended, it is somewhat possible with Adobe 3D Reviewer.
- Right click on the model, select Edit in 3D Reviewer
- In 3D reviewer, choose Export (or Ctrl+E)
- Choose Options (bottom left of the dialog)
- Choose Options again in the dialog that appears
- In the Export PDF Options dialog, check the Use Template box
- Click the browse button (...), which should open the folder containing the default templates that ship with 3D reviewer - which should be in this location - %ProgramFiles%\Adobe\Acrobat 9.0\Acrobat\plug_ins3d\prc\ENU
- Select a template and click OK
- Click OK again
- Click Save
All one needs to do is create a new template and copy/paste the placeholder model from one of the default templates, and size it to the correct dimensions.
It's a long way round, but a nice way to keep models consistently placed, in a nice customised wrapper.