This post is for the eleven people on the planet who care about such things, but here goes nonetheless: my current toning regimen with thiocarbamide and selenium . Tim Rudman's excellent (and currently out of print and expensive to buy used) "The Photographer's Toning Book, The Definitive Guide" has been a bible of sorts for this exploration.
To achieve a chromatic tonal pallette more or less like the PhotoShop filter I've used on the more recent negative scans below, a variable sepia toning process can be used. It involves purchasing the chemicals: thiocarbamide, potassium bromide, potassium ferricyanide (no...it won't kill you unless you're stupid careless), and sodium hydroxide (which will burn your skin off in a trice if you don't wear protective gloves, goggles, apron and magic amulet..it's commonly known as lye), and those were purchased from Photographers' Formulary. Dr. Rudman's book gives a recipe for a stock solution of the bleach, toner, and activator, but the adventure lies in tweaking the brew till it suits one's taste (aesthetic taste, of course). Here's what I've settled on for the moment, which may change a bit as I get familiar wtih it on different images:
Pot Ferri bleach: 10% solution for 30 to 40 seconds
Thiocarbamide toner with Sodium Hydroxide activator" 950 ml of 9 to 1 dilute toner with 50 ml of activator for 2 minutes or until full redevelopment seems to have been achieved.
Thorough washing need to be done between each step, and then a 4 minute bath in selenium 1:10 and a final 30+ minute wash.
Serve with coffee or scotch depending on the time of day.