Try leaving him a message in one of his gallery uploads. Most people have it set to be notified of comments.

I've done that as a last resort asking them to check their site mail, and managed to get the person to contact me that way.

http://www.renderosity.com/mod/gallery/browse.php?user_id=17404

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi