Start: You need ankle straps, dumbbells, a cable-crossover machine, a bench, and a little bit of patience as you get yourself into position. Put the bench between the pulleys. Select fairly light weights on the stacks. Fasten the straps to your wrists, hook the straps to the low pulleys, pick up two light to moderate dumbbells, lie on the bench and hold the dumbbells at the sides of your chest.
Finish: Execute a standard dumbbell press, as described. The extra challenge, of course, is the simultaneous vertical resistance from the dumbbells and horizontal resistance from the cables. Pause, then slowly lower the weights to the starting position.