Hi All, Could someone point me in the right direction of a way to draw a realtime line graph and overlay it on a clip based on some scripted variable? Or maybe if I could screen draw I could work something out in ScriptClip.

You would have to write a plugin to do this. An example can be found in the plugin (source code is available).

Overlua can draw all sorts graphics on a frame by frame(over the video) basis in avisynth. What kind of data do you want the curve to illustrate? The docs are a bit limited, but thare are are some examples to get you started. Check it out: