Thanks for replies. I wondered if I would have to fake it somehow. Your example does go some of the way towards it, and it could be improved further if the glow intensity faded with distance, to simulate the GI glow that occurs in the corners where objects meet.

If the SSS channel is using a greyscale shader to create the marbling, this could be copied to the translucency channel with an appopriate value to create something more realistic.

I haven't explored the Translucency channel yet - might that offer a solution? Am not sure how the light-transmitting properties of SSS might differ from Translucency in the relevent shader properties?

Thanks

Richard