Smoke with Particle System

Hey there…
I am a bit desperate… I want to create smoke with the particle system in blender. I know, there is the smokesimulation. But for my purpose its to slow and the cache is to buggy for me.
I am really satisfied with the result of my actual smoke test, one thing I just don’t get to work. How can I fade particles to alpha zero over their lifetime? Isn’t this possible in Blender 2.5?
In 2.49 I just have to create an ipo curve and it is mapped to the life of a particle. In 2.5 it is mapped absolute, so my whole smoke emitter changes color/alpha etc.

If somebody has already tested this, please give me a hint!!! I think this is an elementary function for particles that need to work!!

So here is my testblend. You just have to play he animation and render.