I installed your fantastic mod.
I have a problem with htaccess file. I set the forum in site.xx/phpBB3/ directory.
In this folder I found an htaccess without rewrite url.
This is what I can see:

<Files "config.php">
Order Allow,Deny
Deny from All
</Files>

<Files "common.php">
Order Allow,Deny
Deny from All
</Files>

This is just the default phpBB3 .htaccess, only meant to add some more protection on sensible files.

The one you'll generate in the acp will include these security precautions, so you can safely overwrite it or leave it there in case you upload the phpBB SEO one in the domain's root (above phpBB3/ dir), which is default.

Ok, I put the htaccess on phpBB-seo cache folder in /phpBB3/ directory. But this don't works.
valent.netsons.org/phpBB3/

The .htaccess is by default meant to go in the domain's root, eg one level above where you put it.

If you do so, make sure you do not leave any .htaccess in the forum dir.

You can as well generate an .htaccess meant to be used in phpBB's dir, try the "more option" option in the .htaccess generator.

Aaaaah, thanks!