although I use http://www.persistentillusion.com/blogblog/techniques/magic-cast-on/magic-cast-on-2
exclusively now for toes.
what I do is cast-on approximately 1/4 of the total amount of stitches for Judy’s Magic Cast-On, you can do more or less for a pointier or wider toe. for 54 (I believe this is the foot number, modify if needed, I sort of skimmed the pattern for the pertinent numbers,) I would do 13(26), increase up to 27(54), then you can start the directions for the foot until desired length. I like to work 4-6 rows of stockinette after the toe increases are completed before beginning any pattern/colorwork. Then, use the calculator/pattern from Knitty to formulate your heel, and continue from there. Since it’s not being worn, the only important thing is having the correct amount of stitches to work the colorwork pattern and such, so you can use the calculator from Knitty as a guide for heel and toe and fudge as needed, but that should give you a pretty good basis. Let me know if I can help further!