this tutorial will definitly solve your problem
http://en.bainternet.info/wordpress-taxonomies-extra-fields-the-easy-way/
Yes i have used it to add feature images to the custom taxonomy terms.It depends how you registering the custom post .If you have registered the custom post as plugin from plugin directory , then you need to paste the downloaded folder i.e Tax-meta-class in directory of your custom post.
Other wise you may also copy Tax-meta-class in theme directory and register the post form functions.php
And i don’t think that it needs to be used like a plugin.
Just one problemO . Every thing is working fine on localhost but when i transfer my the site to live server then i am unable to get the images.May i need to upload the files again
Waiting for the author to reply
If you don’t face any problem let me know.
alll d best