How can I remap the right mouse button to the left mouse button?
What mouse? Apple's Mighty Mouse is configurable as a one-button mouse. For other mice, look at the USB Overdrive mouse driver. It's an amazingly configurable driver for mice, trackpads, joy sticks, game controllers, and other HIDs. I used it with a Kensington multi-button trackball before I had the OEM driver for it. I'd be surprised if you couldn't configure most any mouse as a one-button mouse.