http://bugs.winehq.org/show_bug.cgi?id=20736
--- Comment #8 from Luke Bratch l_bratch@yahoo.co.uk 2009-11-19 15:45:44 --- The ImageAddCertificate hack no longer works to install/run L4D2 (in neither 1.1.33, nor the latest Git). The terminal output is exactly the same as the first attachment.
This seems to be caused by the latest Steam update (http://store.steampowered.com/news/3136/), which does indeed include installation related changes.