After using the P30 kits for a few years I've been playing around with my own developers in order to resolve the contrast issue. Results so far show promise. Firstly the developer is basically a normal B&W developer with a small amount of thiosulphate added to remove the masking layer. Personally I've been testing with the Beers formulas which for lower contrast uses only the metol developer, with the thiosulphate added at a rate of 0.1 to 0.2 grams per 100ml of developer (ie 30ml Beers A stock + 60ml water + 0.1 gm thiosulphate). This develops a silver image in the paper for each of the three layers. I can't see any reason why you couldn't use a normal multigrade type developer (with thiosulphate added) if you're happy with a normal contrast image. Dilution and time can be used to tweak things slightly. You can also use phenidone/ascorbic acid developers if you have a reaction to metol.
For the bleach I've been using the P3 version which needs to run either longer or at a warmer temperature than the normal P30 bleach. The bleach removes the dye from the paper where there is metallic silver and at the same time converts the metallic silver back to a silver halide. Also although it requires a higher temperature or longer time and does deserve respect I prefer the P3 bleach as you can mix up enough for the job at hand. You do need to neutralise the bleach by adding sodium bicarbonate (or similar) before disposal. Ensure there's adequate ventilation.
The fixer step is normal rapid fix at 1+9 dilution. This is a simplistic view of the process but it seems to work. The filtration values tend to require more cyan/magenta than the standard P30 chemicals however the ability to control contrast at the developer stage is a big bonus. Ilfochrome still suffers from slight colour crossover (cyan highlights, red shadows) with E6 films although it's not always noticeable and some films are more prone to the problem than others.