EA-7 with external midi keyboard

[Rolandski]

I like the EA-7 but hate they keys. I understand not putting weighted keys on this, but why doesn't Roland have normal sized keys on its synths?
Anyway, I have not been able to figure out how to simply use a midi keyboard instead of the instrument's own one; both to play whatever and to set the harmonics for the arranger styles, so simply replace the on-board keyboard input with midi. Please advise me if you know how to set the midi settings for that.