Node based DOF on external renders?

I am doing a project at school where we have to use Maya and Mental Ray to render a multilayer EXR sequence, then bring the sequence into Nuke to add post process glow, AO, and DOF.

Working from home I do not have access to Nuke, so I decided to try to do my post pro in Blender. This went all fine and well until I discovered that there appears to be no way in the defocus node to set a 2D focal point using a depth pass.

Is there anyway I can set my focal point with nodes, or must I wait until I can access school computers again?

If there is no way, this seems a bit of an oversight on the developers part and makes it harder to fit Blender into a workflow where it is only used for compositing non-natively rendered content.

Thank you for the link. I am currently using Bartek’s depth subtraction method, I will have to look into making his more complex tree for blurring on both sides of the focal point. May even figure out how to modify it to allow making the DOF shallower/deeper.

For the moment I’ll stick to using Nuke at school when I can; it is somewhat disappointing to have to use a workaround in Blender to get it working.