What do i need exactly for ethercat ? Recommended hardware??

My personal experience thus far is that it is an awful process. I tune them to the same parameters since the JL/JM inertia estimation is almost identical.

Process (roughly):
-Movement only through linuxcnc as two joints on one axis (Gantry mode)
-Using a notebook with asda tuning software, connect to one drive via usb
(A) -Move the axis using linuxcnc and check following error
-determine adjustment and edit servo 1, then switch over to servo 2 and perform identical adjustment
Repeat from (A)

Two notebooks are advisable, as you well spent a lot of time fiddling with the serial cables and reconnecting.

In case of the delta servo drives , if you are using the A2 series , if I'm not mistaken they have a dedicated port for gantry control.

www.deltaww.com/en-us/FAQ/2076