Just to note down my experiences.
I have vBulletin 3.6.4 and Photopost Pro 5.6.2
I have vB installed in root/forums and Photopost installed in root/photopost
I've installed the mod straight as it stands and followed the install instructions.
It installed perfectly, but thumbnails didn't display at all.
After some investigation I saw that the thumbnail URL was not formed properly.
I edited the inc_vbcat.php file that goes in the Photopost folder and made the following corrections.
From:
PHP Code:
<td style="background: url({$data_dir}{$pcat}/thumbs/$photo)
To:
PHP Code:
<td style="background: url({$data_dir}/{$pcat}/thumbs/$photo)
Note the added slash between the {$data_dir}{$pcat}. The above correction needs to be made in 2 places, when you open up the file to edit it should be easily apparent where they are as they are close together.
Hope this helps someone with the same problem.
Mod works a treat though and is really great.