Successfully installed on Zen-Cart 1.5.5f with TPP, SitemapXML. Slight change to .htacces:

# Handle all other URIs using Zen Cart (its index.php)
Changed:
RewriteRule .* index.php [QSA,L]

To:
RewriteRule ^(.*)$ /index.php?path=$1 [NC,L,QSA]

After main page was giving an error/not showing up.

I thought it might help someone else.