Add To Playlist Button Customization
Design and Skin Customization
Those buttons are controlled by CSS and the jrCore_icon function.
The images for the buttons are located in the modules/jrCore/img/icons_black and icons_white directories. To choose which color and size to use for your skin, you would modify your skins/YOURSKIN/include.php file, and modify the code that controls the sprite.
Using jrElastic as an example:
jrCore_register_module_feature('jrCore','icon_color','jrElastic','black');
jrCore_register_module_feature('jrCore','icon_size','jrElastic',30);
The CSS for the sprite, the gradient color and border etc..., is in your skins/YOURSKIN/css/core_form_button.css file and is the sprite_icon class.
If you want to use a different image, you would need to modify the template that the jrCore_icon function is in, and replace it with your image.
Hope this helps,
Douglas