This doesn't need to be written in MATLAB.
The behavior need to be as follow:
A GUI appears on screen and you can see the plot of the head.
We assume that the data to analyze come from the same headset. This need to be enforced when loading the EEG data.
Furthemore, the .SET file have an location associated with them.
Then the user can select which electrode he want to include or exclude from the analysis by clicking on them.