One way you can use the Pigment Sticks is to treat them as if they were regular tube oils or use them in combination with tube oils. But you hold them in your hand. You can work on any surface you would an oil. Use brushes, solvents, and rags once the paint is on the surface.
Many people dip the sticks in mediums or Alkyd driers and then attack the surface.
Some people use them to start a painting with a quick sketch. Some will do their painting with tubes and brushes and then put in final details and lines with the sticks. And depending on how you use them they can be used up fast. But they are a high quality, handmade product that compares very well with other oil paints. Many people buy Pigment Sticks and use a palette knife to cut off small amounts and mix on the palette just like a tube oil.