So, how to do this?
Your feet are constructed practically the same way as your hands. You have the same muscles, bones and other things.
1.) you need to strengthen the non-dominant extremities and train the flexibility.
Do these exercises with all four extremities
2) Start using your NDEs. Look at how babies learn to use their hands. Do the easy things with the NDEs, like pushing the elevator button or opening doors.
Here's a lot of ideas and exercises, designed to teach babies and toddlers the fine motor skills. Things like these are also used with adults when they lose the use of their dominant hand.
3) Bind your dominant hand so that you can't use it, for an hour every day.
Bind your both arms so that you must use your feet to do all the things you want to do.
4) Practice each and every day.