2004 Hyundai Elantra Timing

About a year ago I started having a speed sensor malfunction. The engine light kept coming on. I was having problems with the car changing its gears like it was supposed to, I would get heavy rev then a jerk when the car finally shifted. Last week it got really bad. I was losing power and couldn't make it up a hill at all. I got it home and replaced the speed sensor and the cam shaft position sensor. The car refused to start at all after that. At first I though the exhaust was plugged but we cut a hole in the exhaust in front of the catalytic converter. The car still wouldnt start. I pulled the upper side of the timing belt cover off and found that the belt was missing about 6 inches of teeth. I replaced the timing belt and tried to set the time but the cam pulley is old and the markings are worn off, how can I set the timing on this car without a pressure guage and with out knowing the exact placement of the timing lines.