Image Block to give "must login to view pictures" if non-user is viewing

Hi folks,

I originally posted a similar topic under permissions (http://gallery.menalto.com/node/81831) but saw it fit for here and hopefully clarified the issue.

The situation:
Using G2.3rc
Using drupal 6.4
Using Gallery Module

I would like the G2 image block (via integration) to show the thumbnails for everyone. However, when a non-registered user clicks on the image, it would be nice to have a "you must register to view images" default.

Does anyone have experience in setting this up whether or not it's through current permission combinations or modifying code?

Thanks,
James

www.seaandsnow.org