mouse do not auto-repeat.
keyboard buttons auto-repeat at an operating-system-defined rate, or not at all if the engine disabled autorepeat for some reason. auto-repeat repeats at the same rate as in the console or in notepad. key bindings will not fire from auto-repeated keys, which is one of many reasons why you should still use the engine's key binding system instead of enforcing your own vision of keys on people.
do not depend upon keyboard auto-repeat for anything other than text entry - failure to stick to this rule means that people can just go into their windows/etc keyboard settings and just crank up their key repeat rate to make things super spammy.
it could be replicated if you implement a timer in your own code. either in the csqc, or in the ssqc. preferably the ssqc, which will help smooth intervals between firing - just as the vanilla ssqc does with button0.