A, I can tell you where to get aniline dye but I sure can not tell you haw to use it on stone. Woodcraft has local stores in some cities and a web site at www.woodcraft.com and they sell water soluble. Woodworker's Supply (800-645-9292) is a catalog house and they sell water, alcohol and oil soluble. Since these are both woodworking retailers, they didn't have anything on dying stone.
You might want to visit local stone masons in your area to see if they can give you some direction or try several of the search engines on the web like ask.com to see if they have any sites that might be of help.