To be honest, it really has to do with the OP knowledge and if he is able to understand how to convert his keypad to use an analog pin. If he is unable to do so, then its better to use the standard digital method, or the method you pointed out with the 74hc922 chip.
It is quite a hassle to convert a standard keypad to a analog keypad, if you don't know what you're doing.
But now he has options to go about and solve his problem.