This is what I use on my E3D Tool Changer, which is also CoreXY, running RRF 3.01beta1:
; Endstops
M574 X1 Y1 S3 ; Set X / Y endstop stall detection
M574 Z0 ; No Z endstop
...
;Stall Detection
M915 H200 X Y S3 R0 F0 ; set X and Y to sensitivity 3, do nothing when stall, unfiltered
The XY steps/mm is 100 and the speed (F parameter) of XY homing moves is 3000.
HTH David
