Show shipping method based on product type

Hi Friends,
I need to show only flat rate shipping method for a product type how to do this

What happens when you have mixed Product Types in the same order? :unsure:

I sell different products with different shipping methods(large products freight,small products UPS). if your purchasing a small product both shipping methods appear in checkout. how can I stop that.

In the shipping modules you will see the $this->enabled ...

You can set conditions on that to set it to false so that the shipping module does not show ...

Can you explain this a little more. I do not understand what this will do or really what you are suggesting. This problem is asked over and over in the forum and there does not appear to be an adequate answer.
"You can set conditions on that to set it to false so that the shipping module does not show ... "

You might look at this thread that shows several ways to control the $this->enabled and adapt it to the products_type ...
http://www.zen-cart.com/forum/showthread.php?t=85379