I think that there is even an easier way to do this. You have to call our plugin at the above place. Is $this->vars available in all virtuemart template? If so, then when you call the plugin Shop.browse, the plugin will automatically recognize that this is not single view, it will show the write comment text and also will count the comments for the specific item.
Thanks for the response. I tried but it displayed an error in josc_com_virtuemart (surely due to what you're saying: that array not available).
$productArray = array_merge($category, $vars, $this->vars); says that 3rd parameter is not an Array.
Anyone knows how to get $this->vars available in shop.browse or directly to browse_1.php ??