When Penny was little I'd roll her onto her back and pin her between my legs gently but firmly if you know what I mean. I would hold onto 1 paw until she had finished wriggling and put the other hand on her chest just so she knew I wasn't going to give in. When she relaxed, which didn't take long I would do each paw underneath, then make a big fuss of her when she stood up.
Now with the 3 of them, if I sit on the floor in the kitchen they know it's feet or knots under the pits time and just queue up. They have the same routine for the hair dryer and the grooming table.

Start
Start your routine early even if you can only manage one or 2 feet ATM their co operation will increase in time.