The problem is that we don't know with certainty what causes kava dermopathy. One of the proposed hypotheses was that it interferes with cholesterol metabolism, but there are several other plausible hypotheses and even some that haven't been introduced or investigated. The only point I made about that was in this post (quote below).
All steroid hormones contain a cholesterol backbone, but there are five separate and distinct subtypes of steroid hormones, only one of which is androgens, and within that subclass, there is testosterone. My point is only that it is relatively far removed from cholesterol in relation to testosterone, specifically.
It's that old adage correlation does not equal causation....
Cholesterol, is involved with a vast array of physiological functions, biosyntheses, etc. I think it would be too much of a jump to postulate that exogenous testosterone will prevent or stop the dermopathy.
That being said, there was a pretty interesting suggestion made by Ruze that kava interferes with cholesterol metabolism which causes the skin changes which are similar to lipid-lowering drugs (referenced one in particular, triparanol).
This study, which studied the effect of triparanol on rat skin found results extremely similar to kava dermopathy.
http://www.jlr.org/content/4/2/160.full.pdf
"Kava Dermopathy"
(http://www.ncbi.nlm.nih.gov/pubmed/8021378)