After getting through the installation failures and all the various amenities we've seen in the last week or two I finally got the game working but I was getting a lot of crashes in game both single and multiplayer, especially multiplayer.
I got rid of the single player crashes by adding the cl_forcepreload option to my autoexec.cfg as pointed out in another thread.
The game though was still crashing in multiplayer mode (above all coop and versus) but then i came across this page in steam's forum.
Read the instruction carefully.
There is no real problem with the config file per se but read with care the launch options part of the page and do your math right when messing with the -heapsize option.
I also disabled the netstat graph in the Kaizen's autoexec.cfg since i found it annoying.
The game now is running smoothly both in single and multiplayer.
Tested on Crossover Games 8.1.3 Mac.
I'm off killing zombies now.
Cheers