How to use 1.47.03 render elements?

[MegaPixel]

I know 1.5 has a new render elements feature that behaves similarly to the way the scanline does it (and this sounds awesome!) but my question is how do those of us still using 1.47.03 or earlier use that little area inside the color mapping rollout that looks like an itemized render element selection box? I assume you need to use the Vray VFB to create and seperate them, but saving them out after they are rendered is an issue for me. It seems that when I save out the individual rendered channels, like "reflection" for instance, I get nothing but black when I open her up in PS - even though I can see the reflection isolation quite clearly in the VFB. What am I doing wrong?

Thanks - Dave