The trouble is, part of the beauty of a happy accident is that it takes no effort... :) I doubt the same will be true when you try to replicate it.

As grichter says, highlights which are 'baked' into the hair texture can be a hindrance. Sometimes they work for you, sometimes they don't. There was some discussion around this subject, but I don't recall any real conclusion being reached.

I sometimes remove the texture map from transmapped hair, and leave just the transparency and a solid colour. This looks muddy by itself, as if the hair hasn't been washed recently, but you may have some luck adding your own specular effects back into that mix.