benmanson.com/review/di2/di2buttons.htm
That's old 5-wire DuraAce 79xx Di2, not new 2-wire CAN-bus E-Tube Di2.
Yes, to do the same with E-Tube you need to use the SW-R600 and fit flying leads to it.
@Brommers started
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That's old 5-wire DuraAce 79xx Di2, not new 2-wire CAN-bus E-Tube Di2.