rel=canonical link-tags: Need for site with no access to individual-page headers

The subject website is a Prostores e-commerce CMS site. The headers are not customizable for individual pages. I think that a solution may lie in using the .htaccess file. However I have searched very diligently trying to find the exact syntax to use for the code or tags in the .htaccess file for pages that do not exist as individual files (unlike PDFs or image-files): The FilesMatch syntax works for "pages" that are files such as PDF or image-files: Header set Link '< http://www.mysite.co...rel="canonical"' However I do not know how to apply that to product pages that are derived out of a CMS: The end of the URL of these product pages is: /detail i.e., these are not standalone html files. Your solution could be that you know how to add rel-canonical link-tags to the .htaccess file, for CMS-generated pages with no .htm or .html extension. Or if you have another solution, please feel free to bid on the project. Thanks for your consideration -George