Marko you may have already seen this on the Bostick&Sullivan site, but check this article out. In it there is a discussion of Mike Ware using ammonium chloroplatinite (not ammonium chloroplatinate I realize).

So you might try contacting Ware or even Sullivan or Weese to get their input. Like Don, think it is possible, just not sure what the results will be. Let us know how it works out.