I found an implementation for this in IKEMEN GO Nightly. It still reads as the player getting hit, but the player does not change states. I'm not sure how to add a flash/shake effect, though.
[State ????, HitOverride]
type = HitOverride
trigger1 = 1
attr = SCA, NA, SA, HA, NP, SP, HP, NT, ST, HT
keepstate = 1