I mix Pyrocat HD myself, but you can buy it from the Photographers Formulary either as a powder kit or mixed as liquids. The advantage that it has is it's a staining developer. This means part of the image is made up of stained gelatin along with the rest being silver grains. Because there is less silver grain you get smoother, less grainy, images. Probably best to try it out for yourself to see if it works well for you.
So, in theory, could you add the staining chemistry to something like Rodinal to get a finer grain image with a Rodinal look?