I've never did Source Lighting before but it was actually rather easy and just a thing of minutes. I took this Skavenslave test model I'm messing around with for some tme (ignore the fact that a Slave might never get his hands on a precious shard of Warpstone) and basecoated the Warpstone with Dark Angels Green. Then I layered Snot Green and highlighted with RMS Jade Green, VGC Scorpy Green, VGC Livery Green and P3 Morrow White. If you just got GW Snot Green, Scorpion Green and Skull White mix the intermediate stages.
For the actual glow I washed the affected area around the Warpstone with Thraka Green. Then I applied several thin coats of Snot Green to the raised areas that catch the light. Take care to get closer to the light source with each further step of highlighting. For the most prominent parts, I used a little bit of thinned Scorpy Green. Then I applied another glaze of Thraka Green.
All in all quite easy to do. I might do a more comprehensive, step by step pictured tutorial at one point though!