It is possible, but only to a limit. The ticklishness of the feet is partially physical and partly psychological.
1. Physical: you can make your feet more sensitive by getting a pedicure and ask them to use their callous pad/sponge on the soles of your feet. By keeping the dead skin debred away, you make the bottoms of your feet a little less protected. You can also use foot creams on the bottoms of your feet.
2. The psychological. Through meditation and relaxation therapy where you visualize your feet being ticklish, you can become less guarded and there for tickles. One exercise you can do is to sit in a darkened room, with little or no cloths, blind folded. Then have a partner or trusted friend, use a feather and a few other light objects to lightly trace your skin in different places. The idea is to let go of fear, to allow yourself to feel, and to describe what you feel; allow yourself to laugh at what feels good. eventually they can reach the bottoms of your feet.