Since Cycles is the ‘new hotness’ we naturally don’t want to exclude using it for our renders. However, Cycles lacks some features and support that Blender internal has; such as SSS, volume shaders, strand rendering, particles, A.O. and probably more. In order to use it at all we’re going to have to combine our renders, and we need a good way of managing this.
One side of this is the compositor: you can put a Cycles scene into a file, an Internal Scene, and then render them both from a third, compositing scene, that pulls in renderlayers from both. So far so good, but! if you have have objects linked into both scenes, what to do about materials? Cycles materials and Blender materials are different… or are they?
Turns out nodal materials are our friends, because they can contain both Cycles shading nodes and Blender internal nodes… nifty, right? so all you have to do is use nodes in internal, and then both will work.
If you feel like you need more in depth explanation, check out the video tutorial below, and download the included .blend file.
EDIT: New .blend file! includes solution to the emission problem: download here