Just my Autoexec so People can use it if they want :) Most Stuff is copied from other cfg's so don't expect to much.
Put the autoexec.cfg in C:\Steam\steamapps\common\Left 4 Dead 2\left4dead2\cfg or wherever you installed your Game. Anything else is in the cfg explained as much as i could.
For all the other configs create a folder called configs in the cfg folder and drop them there.