Thank you for posting this ebuild, however on my system the deb converting process fails and I'm not yet sure why. I simply got around that by doing the conversion manually and editing the ebuild to use the finished tar.bz2 instead of the deb file.
Furthermore, in addition to the deps you'd written in the ebuild I had to emerge qtwebkit before the game's launcher would run. Still, after getting the launcher to run, it simply fails to patch the game on my system. I'm assuming this went without a hitch on yours?