How to cache POST requests with Boost
You would need to do 2 things. Create your own hook_init that runs after boost_init to modify the global $_boost['cache_this'] value &amp; use hook_boost_cookie_handler_callback_alter to write your own boost_cookie_handler function that works with POST.

To check if the page exists in the cache the boost_block_view_status() function has the parts needed but it has not been abstracted out so you would need to create your own function to do this.

That will cache POSTs.

If you want to serve from the cache on a POST (ignore the post) in your htaccess file remove RewriteCond %{REQUEST_METHOD} !^(GET|HEAD)$ [OR].

A lot of things can go wrong if doing this. It's a bad idea 99% of the time.