noise modifier for a node value

I want to add a noise modifier to factor in a mix node. It doesn’t show up in the graph editor. How can I do it?

For a modifier to show up in the graph editor you need to have at least one keyframe for the channel. So rewind to frame 1 and insert a keyframe for the factor. Then move your mouse into to graph editor and press the N-KEY. Scroll down to the bottom of the numeric input panel and click Add Modifier and choose noise. The noise will be centered around the initial value of the keyframe. So you may want to set your Mix factor to 0.5 before your insert the first and only keyframe.

Add Input - Value to drive Fac; that could be driven by python driver in turn. http://vimeo.com/40389198

I diddnt have the node selected in the node editor, thats why it wasnt showing up. Thanks!