To install:
  1. Make a copy of your Photoshop Elements 2 Recipes index file
     -Usually C:\Program Files\Adobe\Photoshop Elements 
2\HTMLPalettes\Recipes\index.html
  2. Copy P600.zip to the folder where Photoshop Elements 2 is installed
     -Usually C:\Program Files\Adobe\test\Program Files\Adobe\Photoshop 
Elements 2
  3. Now go to that folder (such as with the Windows File Explorer)
  4. Extract P600.zip in that folder
     -Answer Yes to replacing the index.html file
     -In addition to placing all the files you need, it'll replace your 
index.html file
      and place a copy of the original that came with *my* PE2 in a file 
called
      origindex.html.  Step 1 above is for extra safety on the remote chance 
that your
      index.html file differs from mine.  It's a good idea to replace 
origindex.html with
      your own copy if they're different.
  5. Next, run Photoshop Elements 2 and open an image file there
  6. To apply Gene's vignetting and distortion corrections, go to the How To 
tab
     near the upper right part of the PE2 menu, select P600, and follow the 
link
     or click on the picture

If you're running Ling Nero's LUI tools for Photoshop Elements 2:
  1. Expand the P600 - LUI Tools.zip file in an empty temporary folder 
somewhere
  2  Move the UIImages\P600 folder to your PE2 UIImages folder
     -Usually C:\Program Files\Adobe\Photoshop Elements 
2\HTMLPalettes\Recipes\UIImages
  3. Move the ex_p600.atn file to your PE2 \Presets\Photoshop Actions folder
  4. Move the P600 Corrections.xml file to the LUI \add folder
     -Usually C:\Program Files\Adobe\Photoshop Elements 
2\HTMLPalettes\Recipes\LUI\add
  5. Do the usual LUI integration jazz by running snapActions.exe or 
snapActions.jar,
     moving the P600 menu item on the left to the right-hand (Active) side 
of snapActions,
     and pressing the Generate button


You can get Ling Nero's tools at:

http://www.geocities.com/rnlnero/PE2stuff2.html

Bud Guin's PS/E goodies (he gives some background about Ling's stuff, too):
http://www.retouchpro.com/forums/showthread.php?s=&threadid=5221