Try this (you seem to already know about . silencing commands):
Code:
on *:TEXT:*:#mychan:{
  if ($1 == !FAQ) .play -n $nick c:\InvisionOLD\Text\FAQ.txt 1000
  elseif ($1 == !clog) .play -n $nick c:\InvisionOLD\Text\MMlog.txt 1000
  elseif ($1 == !latest) .notice $nick http://some_website.com
}

Multiple on TEXT events will not work if their matchtext section (in your case *) are already matched by an on TEXT event earlier in the script.