Chord sets are saved as XML files in Scaler, and I don’t think you can batch import midi files.
So, assuming you still have old machine, copy the chord set files from your USER directory on the old machine into the USER directory on your new machine. You can find the directory location at the bottom of the PREFERENCES tab under SETTINGS.
After copying the files into this directory refresh the User list.
For more information abourt saving Chord Sets there is a tutorial here. Hope this helps.