Hi !
I've done a lot of things with B&W slides.
First I used to process C41 B&W film (Ilford's, Kodak's, Konica ) in E6 chemistry using the time/IE found in an old paper in "photo techniques" Nice looking, without color cast, and smooth subtle gradation. Best results when exposing for IE 100 processed in Kodak 7 baths chemistry (standard stuff) filsm had gone through a custom made dip and dunk line at my camera club, but a friend of mine used a Jobo/kodak process with very comparable results.
I've made copies of B&W negs (slightly cropped using a Bowens repro unit for color slides) on FP4 and TMX. mixed feelings, but cropping possible.
I've tried to mix my own kit to invert normal film. It proved difficult to get the correct chemicals at right price/quantities (less than 100 pounds ;-) ) so I've abandened that way.
A friend at my camera club has used scanning normal B&W negs, inverted (to go back to neg) and tweaked in PS, and output to film in a image setter. PS shows and film output is difficult to master.
I've bought a Foma kit and plan to put into use soon.
Hope this helps.