Very strange assignment.
Definitely not the way to do things.

I can say, the only part of the stack that's available to read/write is the TOS (Top Of Stack).

You can NOT split it in thirds and have 3 TOS's.

To do what you are suggesting, you would need to create your own stacks in software, and POP the entries off the hardware stack, then put them in your own stacks. Then in reverse order, to pop them off your stack.

But I really see no benefit, other than learning. And it's NOT beginners stuff.