Show most recent attachment from a post type.

Hi

I want to be able to display on my homepage, the most recent 2 or 3 images that have been uploaded to my blog, but ONLY ones that are attached to a certain custom post type.

Easy enough to get the most recent of all images, using get_posts, but it’s the custom post type bit I’m not sure about, as you can’t use that as a parameter for get_posts.

Any ideas how I would achieve this?

Thanks