http://bugs.winehq.org/show_bug.cgi?id=27118
--- Comment #1 from JR zorael@gmail.com 2011-05-13 18:16:02 CDT --- A workaround seems to be to run it in Windows XP mode. This is what PlayOnLinux does.
Since Steam itself is easier to deal with if using Windows 7 mode, I added an application-specific setting for both deadspace2.exe and activation.exe to exempt them and make them run in Windows XP mode. The activator now starts (tested via terminal) and properly activates the game.