Don't know how you'd do it yourself within Poser but there are some excellent textures in the MP with wet looks for both M3 and V3 and then there's the wet maps for V4 at DAZ!
I use one called "Drenched" for V3 by Victorias [I think] and I think TamelaJ has a really good one for M3 and you might also try "Faceoff" he may have one, can't remember!!

Probably not the answer you wanted but the best I've got at this time of the day [LOL].

Injustice will be avenged.
Cofiwch Dryweryn.