Mouse Customize or link game

Sorry if my grammar are bad :((((((((((( How do I customize my Mouse for League of Legend for the mouse button act as a Shift + a key or however, is it possible without interfering with the client? so in LOL if we hold shift while right-click is to player attack move, so how do I able to customize my left button as a shift key? their also an issue that I changed my mouse to hyper shift but when I check it was never in the hyper shift. If this article is hard to understand then I'm sorry about that.