Unless you are doing bonsai, you never want to control height on a Japanese maple by pruning - the results won't be pretty and you could introduce to the tree to a number of problems :-) However, a good many cultivars will naturally stay at that height or even less. You need to look for naturally dwarf cultivars or those with low grafts, like many of the weeping laceleafs. Even these may occasionally require some selective pruning to remove or redirect wayward branches but that's quite a bit different from routine pruning to keep a tree that wants to grow taller at a specified height.

Thanks, Gardengal. If the tree is reputed to reach four feet tall in ten years, is that a cap? Can it be kept at four feet, or does that just mean it is a very slow grower?