Makeup will work on silicone, but it will rub off faster. You can use a sealant like Ben Nye Final Seal to prolong your effect, but because the Peecock is silicone, the color won't "seep into" the material as much as it would on a porous Mr. Limpy. This means that when the makeup does wear off, you will have to reapply from scratch. A more long-term sealant idea is to do the makeup, and then coat the prosthetic in a super thin layer of silicone, but this is an expensive option. I tried to use a less-expensive approach: painting on silicone caulking to seal in color on a damaged Vixskin product; it didn't go on smooth and looks very odd. Now I know that you can thin caulking using lighter fluid and other chemicals, but I'm not sure I want to put those near my bits. Try looking into what folks in the love doll, FX makeup, and reborning communities get up to; they all use silicone as a medium and have to apply detailed paint jobs.
(Short-Term) Ben Nye Sealant:
http://www.makeupmania.com/products/Ben-Nye-%252d-Final-Seal-.html#gsc.tab=0(Long Term) Dragon Skin Platinum Cure Silicone Rubber:
http://www.smooth-on.com/Silicone-Rubber-an/c2_1115_1339/index.htmlNote on the Dragon Skin: I've not tried this, but the product seems to be very popular and is $30 for a trial size; maybe someone with more mold-making/casting/FX skills can help out with more information?
