question about image space modifier

[Ellavriel]

I ve been trying to apply image space modifier to a potion, but since Im a total noob in scripting I have no idea how it should look like.

I found this thread: http://www.loverslab.com/topic/44807-how-to-apply-a-simple-black-screen-anytime-you-want-tutorial/

that script looks really simple, but how do i set time for the effect duration?

in other words, any info/usefull guide link on a subject will be appreciated.