Preserving unmatted edges and interlacing in nodes

Blender’s internal renderer will render interlacing and unmatted edges (the ‘key’ setting) without a problem, this does not carry over into the nodes compositor.

Blur effects in particular, but really all of the processing done in the nodes are set up for single progressive frames and with soft prematted edges. I do most of my final composition outside of blender, often over interlaced video, and use the nodes for additional image control rather than for composition. I really like what I can do with it, but blurs feather interlacing and the harsh unmatted edges I’m trying to preserve without maintaining these formats. Is there any way of setting up blender’s post effects the way I need them or is such an option going to be available any time soon?