The Wii version of Call of Duty: Modern Warfare 3 (developed by n-Space) uses a unique control scheme built around the Wii Remote and Nunchuk—it is not a direct port of the Xbox 360/PS3 versions.
There is no option to use a "traditional" controller layout. The game is designed exclusively for Wii motion controls. You must use the Wii Remote and Nunchuk as intended.
Pointer aiming offers precision analog sticks can't match, but requires adaptation. The n-Space version has unique level design, enemy placement, and pacing built around motion controls. It's a different game, not a worse port.