Thank you for the suggestions but I have tried both with little success. The thing is that I was looking mainly for the streaks of sweat running down his body.

I finally took the time and converted a V4 pack for him but there's a region in his back that for some reason ends up dry. It's also not very visible with SSS but I can live with this. The good thing is that this way I can use these wet maps in any M4 texture with just a click.