Very patiently, I guess. If it's stuck all the way down, with not even one loose corner, attack from the edges and don't skimp on the oil. Eventually the oil disperses underneath across the adhesive layer so you can lift away a little, put down more oil, wait, lift away a little more tape, etc.
This is the type of advice that won't make sense until you're trying to get a piece a tape of of someone's scalp.
Reference: Mazola in Medicine, by Art E. Choak, M.D., Tom Maytoh, Ph.D., and Rudy Bagga, M.D. Gore-Gaia Press, Nashville, TN. (2003)... 8~)