If you've got metaforms you could use that for dirt. And also if you have Poser 5 (sorry I can't remember if you do) you could use a modified version of Ajax' slime shader

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You just can't put the words "Poserites" and "happy" in the same sentence - didn't you know that? LaurieA
  Using Poser since 2002. Currently at Version 11.1 - Win 10.