The INT-1106FE Dual Action Tactile Switch is the perfect low-profile shoulder button solution for your Wii portable! These switches are intended to be used with GC+ 1.0 or GC+ 2.0. In the case of GC+ 1.0, a custom firmware is needed in order for the switches to operate as intended. This firmware can be downloaded by clicking here!
Please refer to the GC+ documentation for how to update your GC+ controller. It can be found here.