Begin prone with the foam roller beneath the mid to upper thigh. Initially, position the leg in neutral (foot/toes pointing straight down to the floor). Next, position the lower body so that the right leg/foot is rotated about 45 degrees inward relative to the start position. This will allow you to effectively roll over the TFL.
Slowly slide up/down bringing the TFL into contact with the foam roller. Keep in mind the TFL will be anterior to the greater trochanter so do not rotate too much or you will be rolling over the outer hip. The amplitude of the movement will be smaller as the muscle is not extremely long. I suggest slowly rolling up and down for 30-60 seconds or simply find 2-3 tight/sore sports and do some steady compression for 8-10 seconds or so on each spot following that up with some general rolling.
Many people argue the effectiveness of foam rolling the IT band itself. While I am not inclined to ignore it altogether, I do believe that foam rolling probably has a far greater impact on the length/tension of the soft tissue beneath and associated with the IT band (e.g. glutes, quads, hamstrings and TFL). TFL dominance is a common issue I uncover in my assessments and the muscle is often full of trigger points. Employing some routine soft tissue mobilization will help reduce hip flexor tightness and help reset the neuromuscular system and set the stage for enhancing preferential gluteus medius activation during training exercises.