If you can't do a clean-grip snatch, you need to work solely on shoulder flexibility. Also, your lower back will have to have significantly more strength to handle the same amount you normally split/push jerk.
Put 5 kg on either side of the bar. Work on close-grip overhead squats, holding in the furthest position down you can get. After about a month of constant stretch work you should get it if you're decently flexible.
I only work push/power jerks now that I squat jerk. Push jerking is a great way to practice the balance aspect of the squat jerk. They are both the same exact movements. The only difference is you can, once strength is heavily built, drop into a squat to catch the weight and give yourself a "second chance."
Try your best not to rock back on your heels when you're in the hole. It breaks your lumbar position, leading to a higher chance of injury and much higher chance of getting a red light.
If your glutes, upper thighs, lower back, shoulders, or triceps are lacking any it will be very apparent.