Seems not to be in portage, but belongs to xfce4-goodies
I know. I've tried this plug-in, and 0.0.1 is no good. It shouldn't be added to Portage because it doesn't work at all. It's been fixed in trunk, so perhaps 0.0.2.. or such, is usable.
So why not add it as masked instead, if its unstable?
The main tree is not the right place for experimental stuff, that's what we have overlays for. The xfce4 svn overlay currently holds a live ebuild of xfce4-cddrive.
Closing as LATER, because there is no working release
it needs HAL which has been dead for years.