Here what I usually do:
Take your arm off the unipivot point. Place the jig over the spindle on your platter. Loosen the screws on the jig so that the V-shaped end can be pushed up against the side of the unipivot cup and tighten the screws back down. Place the arm back on the unipivot point and adjust your cartridge so that the stylus is on the small point of the jig and the front face of the cartridge is parallel to the lines on the jig. This is from memory and I don't have my jig in front of me so I hope I didn't confuse you more.
Take your arm off the unipivot point. Place the jig over the spindle on your platter. Loosen the screws on the jig so that the V-shaped end can be pushed up against the side of the unipivot cup and tighten the screws back down. Place the arm back on the unipivot point and adjust your cartridge so that the stylus is on the small point of the jig and the front face of the cartridge is parallel to the lines on the jig. This is from memory and I don't have my jig in front of me so I hope I didn't confuse you more.