RS-482 and RS-422 ESD is an interesting problem. The high
common moderange requires a resistor divider (though I
once had someone tell me they made a receiver that used
no resistor divider, they were unwilling to share details).
The ESD needs to not bind up the common mode input
range. That most likely means an isolated resistor which will
have to be sized for high thermal pulse input, with clamps
inboard of the front series resistor. You will want to understand
the pulsed power input of an ESD event, and the power-to-blow
capability of the resistors. You also need to maintain a good
enough lateral spacing in the resistors (anything that will
see the kV) to prevent spark-gap action, and not put the
resistor under power bussing, perhaps even make the input
pads "custom" (leaving out maybe the first couple of metal
layers at the bottom) to ensure there won't be a Met1-substrate
punchthrough (think 7MV/cm or so).
Standard ESD cells will not help you, they're going to dump
forward into vdd well below your upper CM limit and ground
well above the lower.