if ((DmxToBeatNewLevelLast = 0) & (DmxToBeatNewLevel > 0)) BeatTap
else if, else
Not sure you can (?), but you can do this kind of approach:
if ((extvalue(0,100) > 45) & (extvalue(0,100) < 55)) AnimationSpeed 100 //Fader 45-55% = 100% (nice big deadband)
if (extvalue(0,100) <= 45) AnimationSpeed extvalue (0,222) //Fader 0-45% = 0-100%
if (extvalue(0,100) >= 55) AnimationSpeed extvalue (-260,400) //Fader 55-100% = 100-400%