The platinium/palladium process has been used - using a standard kit from Bostick & Sulliven in the USA. I do not use ferric oxalate solution 2 as a contrast agent on advice from Kerik Kouklis and I will start addingpotasium dichromate to the developer having seperate developers for different contrast ratios. As such, at the moment, I do not adjust the contrast and I have some negs that would benefit from it. Have a look at the website of Kerik Kouklis or Dick Arentz for more info. It is not as difficult - nor expensive - as some would like you to believe but something that you need to spend time to master. Try cyanotyes first - ridiculouly check and great fun - look at Mike Wares site and John Brewer is another - make great T-Shirts for the kids, duvet covers or even curtians etc etc.
All the best, Carl