The htaccess code seems to be working for me.
Example:
http://www.soveratonews.com/fotoblog/liberty
What you need to do now is edit your Pixelpost template and add this code for the next/previous links.
HTML Code:
<span class="image-previous"><a href='/fotoblog/<IMAGE_PREVIOUS_SLUG>'>Precedente</a></span>
<span class="image-next"><a href='/fotoblog/<IMAGE_NEXT_SLUG>'>Successiva</a></span>