Motion blur effect used in Source engine

[Bulletbrain]

You guys know the motion blur effect that is used in source games and mods, for example in Substance( Shell shock effect) or in Vampires: Bloodlines (The invisibility effect). I was wondering whether there is a way to enable this effect manually, at anytime while in-game? I already know of some simple console commands that can be used to edit the nature of this effect (eg: The intensity of the effect) but haven't still found a command that can manually enable the effect.

Thanks in advance.