Changing watermark.jpg location and filename

[ktwalrus]

Can I change so all skins use my watermark.png image without editing the skin CSS and watermark.html in the skin?

I know I can change my logo in the config file (by setting $config['skin_logo']).  Can I set this to somehow include my watermark.png?

I'm using 1.0-rc.

[SKaero]

Do you'd have to change the watermark image file.