Not sure how or if you can do it with the DX18 but on my A-10 with Jeti, I have it set up to vibrate the left stick 3 times for left engine flameout and the right stick 3 times for right engine flameout. I also have a voice announcement for Left and Right engine flameout but I'm not sure it can be heard with multiple jets in the air, which is why I also have the stick vibration alert. I agree with Jesus that you need to program the alert so as not to go off when you first start-up.
FYI, with a twin, it's important to know which engine has flamed out in a critical situation (i.e. takeoff or other low-altitude/high power situation), so you can counter it with opposite rudder (not just aileron). You are wise to have an alert of some sort to warn you.
Craig