Wow this is an old topic. The technique is purely a basic blended highlight with the difference being I used less shades (I believe 4 down from my usual 7 for full highlights on other models) and keeping the first one very narrow to overall give a sharp highlight rather than a long, smooth one. It is straight on chaos black, so instead of extending the first blue layer (regal blue I believe) across most of the carapace, it is just pushed to half of each carapace plate, or less even. Also with that first layer I feathered it, pointing the brush at the edge of the carapace plate and pushing fairly hard there but then pulling off the model as it went it, giving the lines you can see on the largest plate. From there it was just normal highlighting up to lightning blue except working over only a few mm of the model instead of a larger area to keep it sharp. Almost like highlighting the raised areas of armour actually. Its a pretty time consuming technique, and I found it difficult to scale up to larger creatures like the carnifex because you either had large flat areas of black, or a gentle highlight over a large area which didn't quite give the striking dangerous look I was looking for. In hindsight some gloss varnish would probably help a lot, but I didn't use it back when I painted this model.
My synapsis of 40k: Shooting army-75% list, 25% target priority CC army- 50% list, 25% tactics, 25% movement phase
I'm also thinking of starting a small 'nids army to play against my brothers space maries, and I was wondering if the old battleforce ( the one with the carnifex) was all plastic?