You probably need an activator. What I used in toning kallitypes with palladium was the following.
5ml of palladium 20% solution
10g citric acid
1000ml of water
BTW, I made the tests today in toning kallitypes with pure platinum, then bleaching. I reported the results on the largeformat forum. Although I used the toner very warm (at about 160 degrees F) as you had suggested the results were not quite as good as with palladium toning at room temperature.
Obviously there is a lot of room here for experimentation and I certianly don't think the two tests I have done to date come close to telling us the whole story about noble metal replacement.