It's tested only with 1.7.x versions. Indeed, I think it can also work with 1.6 versions, because the only hook it's using was also at 1.6 versions, and it's also using "old" translation system, but I didn't tested it yet. If you want to try, the only you have to do is to open file ftm_cacheclear.php before installation, and modify #30 line from:
$this->ps_versions_compliancy = array('min' => '188.8.131.52', 'max' => _PS_VERSION_);
$this->ps_versions_compliancy = array('min' => '184.108.40.206', 'max' => _PS_VERSION_);
Please, if you test it and it's working nicely let me know to make this change permanent.