Possible? Crazy? I thought it was the same basic code/system, it should be logical right?
yes it's possible, you should read this
http://forum.coppermine-gallery.net/index.php?topic=24056.0
and create a new theme same az the phpbb one
You can make up a Coppermine theme that matches the look of your phpbb-driven forum. However, you can't directly import phpbb themes and re-use them with coppermine. Those two theming engines are closely related in terms of underlying technology (they share a common ancestor). But they're not clones nor twins, more sort of remote cousins.