ya need a looped scroll.
make a tiny script with the playMove looped and an END condition:
_unit = _this select 0
getUp=false
_unit switchmove "FXStandToDip"
~1.7
#loop
~1.3
? getUp: goto "quit"
_unit switchmove "FXStandDip"
goto "loop"
#quit
_unit switchMove "FXStandFromDip"
~3
_unit SwitchMove "Auto"
exit
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And that's it - just make a trigger that reads "getUp = True" in the OnActivation field to stop the looped scroll.
You may have to fiddle with the delays (it's in seconds) to get it right.