I got the plugin to work by installing it manually on a 24" iMac
(Intel). YMMV.

1. Download FileOpenInstaller.dmg from
http://plugin.fileopen.com/current/FileOpenInstaller.dmg and place it
somewhere easily accessible like the desktop.

2. Open the dmg file and copy the FileOpenInstaller package to the same
location as the dmg file.

3. Right-click on the FileOpenInstaller package (not the dmg file) and
select "Show Package Contents."

4. Browse to the Contents/Resources folder. In that folder you'll see
another folder called FileOpen8.acroplugin.

5. Now go to the /Applications/Adobe Reader 8 folder, highlight the
Adobe Reader application icon and press Cmd-i. Click on the arrow to the
left of Plugins if it's not already expanded. Click the Add button,
navigate to where FileOpen8.acroplugin is located and click Choose.

6. Reboot your computer.

7. If the plugin has been installed correctly, when you start Adobe
Reader, click on the Adobe Reader Menu and you should see a choice
"About Third-Party Plug-Ins." Clicking on that you should then see
"FileOpen WebPublisher..."

8. Try opening one of the numerical recipes pdf files. It should work at
this point.

This procedure worked for me, and I hope it works for you too. Note that
the NR pdf files are only viewable under Adobe Reader 8. You will not be
able to view the files in Preview. It sucks, but it's better than
nothing. Hope this helps.

Thanks, noyfb. This should help a lot of people.
Bill Press