I just googled "diafine developer quart" and found that both Glazer's and Omega-Brandess have it in stock, consider calling one of them.
Next, Diafine is a two bath developer. You have to mix the two parts separately and keep them separate. Some of part A will carry over into part B in use, but if you get any of part B (the alkali) into part A, you have to start over.
I believe that the recipes in Anchell's Darkroom Cookbook, like in most recipes, list the ingredients in order of addition.
Lastly, in my copy, I noted that people said the borax in Anchell's part B wasn't active enough and to try another alkali, but I haven't ever used that recipe, so you may want to search photrio for feedback on Anchell's recipe.