Can anyone help me understand how to implement interrupts on a Motorola processor? Is there a preset list of possible interrupts and I choose them by setting certain control bits in preset registers? For example, how would I write a program to enter a routine whenever I pulse a high signal (using a push button switch on a breadboard) to one of the pins of the processor? I would also like the same button to stop the routine. Some sample code would be appreciated also.

i didn't use motorola, but interrupts don't change much from chip to chip i think.
so if you want to make an interrupt, then you need to connect your button to an interrupt pin, then you need to write your code in the proper location of memory. that's all i think.
another way in 80x86 series chip that you signal to IR pin (interrupt request), then send your interrupt address (which your code is located) to the databus.
in motorola they will be similar, i think.