Convert 2D EEG dataset to 4D

I have this EEG data file/dataset named "SSVEPdata.mat " which is a 4D matrix. on the other side, I have this 2D EEG data file/dataset named "S001a.mat".

I want to convert or prepre the second 2D file to a format which is compitable to the first one 4D.

The SSVEPdata contains below info

1) The first dimension is an epoch relative to a single sensor (always 1000 samples, that is 4 seconds, the SR is 250)

2) The second is the sensor.

3) The 3rd element is the trial relative to a class, so that max value is 20

4) the 4th element is the correct label

The S001a is a 2D matrix with 257*117917 which are 257 channels/sensors and the other are readings/recordings per sensor data

Link for both data files: data files URL