Unfortunately, there isn’t a way just inside of Sculptris to get a perfect color match for your purposes. But, I think that there is a slight work around. I know that you can export a psd file from Sculptris (sorry, not at the computer right now to test all of this). If I remember correctly (if you don’t have Photoshop anyway), Gimp will open the psd file as well as export it. Once you have it open in Gimp/PS, find your color and spray a fairly solid bit either where it won’t be noticed or where it will blend in with the rest once you’re done. When you import the file back into Sculptris it will basically projection map that texture on to your model. Just use the “C” button plus left mouse click to choose that color and paint with it inside Sculptris. Might take a little while if you are using a number of colors to repeat the process, but it should work for now.
Haven’t had a chance to open up the computer for a while, but I wanted to test it out to make sure that what I stated would still work. On the plus side, everything seems to work just fine with a slight bit to take note of that I will show in a moment.
First I took a basic model into paint. Just above the model, you can see the “EXPORT PSD” button (which you can drop down by hitting the “Show advanced tools” button just below Brush and Texture boxes).
Opening that file in Gimp, I painted something a bit different on both sides to get a better idea of which side you might want to focus on just in case there was a difference on import. Just find your color and spray it on the “Paint” layer (for this example, I used the html color you had from above). Once done, export the PSD.
And it seems that you should focus on the lighter side to paint on, which is noticeable once you import PSD.
Holding the “C” button and Left clicking on the color, I then used that to airbrush onto the model. So it can work for what you were trying to do.