Because it's no IWnet.
It's different to debug the slowmo gwk code, hence why IW4 haven't implemented it.
Refer to this guy http://fourdeltaone.net/memberlist.php?mode=viewprofile&u=312 His name is RaidMax, and he has the slow mo option on his servers.
Maybe he can help you
Ahh okay thanks a lot man Really appreciate it.