Step 1. Buy largest bag of M&M's available.
Step 2. Give 3 M&M's for every pee in the potty (30-40 for yourself each time, too) and 10 for every poop in the potty.
Step 3. Eat M&M's every time you walk into kitchen, by kitchen, near kitchen, or think of the kitchen.
Step 4. Gain about 5 pounds from M&M's.
Step 5. Realize that no amount of bribery will work if they aren't ready.
Step 6. Finish M&M's and let them run around with no pants until they get it.