The easiest way to use black pepper as a repellent is to simply place little piles of it in high-traffic areas for mice, like inside cabinets, under sofas, and behind your fridge.
You can put the piles of pepper in coffee filters that will serve as little bags for your repellent; mice will still be repelled by the smell, and you’ll save yourself the mess.
You can also mix black pepper oil concentrate with alcohol to make a homemade repellent spray. The referenced study used a concentration of 2% black pepper oil.