Hi Pingo,
now that looks fun :-)
Give Helges MoGraph tools a good workout. Should be possible in minutes as well. :-)
Particles from a spline, Randomizer, AoN:Distance maybe in the weird Object-Mode for automatic variations combined with Helges Random Colors...
But what I found in my many years of software hunting: it is often very frustrating to recreate something from one app in another "exactly", especially if you are more experienced in one of them, since the toolset, strengths and mindset are so different. Helges MoGraph tools are superb and can do things C4D Mograph can't (I love meshtrails :-) ), but the other way around it's also true.
In my experience, Mental Ray is never as fast with simple scenes as Lightwave or C4D, often it takes longer to just initialize... ;-)
But render Ambient Occlusion in C4D and you find yourself drinking more coffee than you ever should... ;-)
Or several millions of polys...
Or really large images in LW...
So nowadays I try to concentrate more on the existing strengths of an app and use something else where it sucks ;-) (or enhance it on my own if possible)
The good thing with knowing many apps is, that you can think outside of the XSI-box, since you have actually _seen_ better solutions... :-)
Well, let me know how the shader works for you.
Cheers,
Thomas Helzle