I'm with Downunder. With a caveat: sometimes you've just gotta split hostas - that happens - every few years spade up some and give 'em to your neighbors, children, or toss them in your compost. If this is your situation, my apologies, too.
But, your plan is a BAD IDEA. Pot-binding the plant will lead to disease and health problems (root rot, insect infestation, etc). There are 100s of Hostas to choose from. I have one that gets maximum of 10 inches across. And I have one that gets 5 feet across. Do some reading a pick one that would be perfect for you, rather than trying to force your poor plant into 'behaving'.
If you need a smaller hosta than the one you have, dig it up, replace it with a more appropriate specimen and be done with it.