The physical requirements to attain mastery of the bent press are numerous. Muscular strength, flexibility and technical skill are needed if you want to lift large amounts of weight with the bent press. There isn't a whole lot out there on bent pressing, and training for the bent press can be challenging if you don't know what lifts to do. There are many different ways you can train the bent press. Your choices will be based on your own needs and preferences. I can give you a list of the lifts that have assisted my own bent press training.
One Handed Snatch and One Handed Clean and Jerk
These two lifts are great for gaining strength and power in general, and particularly good as assistance lifts for the bent press. Arthur Saxon, the great bent presser, thought highly of these two lifts. You can do the one handed clean and jerk and one handed snatch with either a dumbbell or a barbell. If you use a barbell, you'll need to learn how to balance the weight properly as that can be the biggest problem for beginners. These lifts are done by reaching down and thrusting the bar or db clear overhead or to the shoulder and then overhead. The reason they're good for the bent press it that they're one handed lifts that use a lot of the same muscles, and can get you used to doing heavy lifts with one hand.
The side press is somewhat similar to the bent press. To do the side press, you should take a dumbbell and press it overhead while bending to the side. It's a fairly simple lift and hits a lot of the same muscles as the bent press. It's very good for building side, tricep and shoulder strength. While you can do the side press with a barbell, it's better to do it with a dumbbell as the barbell can make it difficult to do many reps at a time. If you're new to any sort of one armed overhead lifts, then the side press with a dumbbell is your best choice for a bent press assistance lift.
Hand and Grip Strength
Hand and grip strength is very important for the bent press, as well as a number of other lifts. A lot of lifters avoid or ignore their grip strength. The reason you need hand, wrist and grip strength for the bent press is because the lift can put a lot of pressure on your wrists, and you need to have a firm hold of the bar at all times. Train your hand, grip and wrist strength can be done in a number of ways. Wrist curls, holding weights overhead for time, or thick bar lifts are good choices for hand strength.
one arm snatch
one handed clean and jerk