FCP/EMP SCAR
Generally, if you read the roll, you punish it with a neutral jump-punch (like Sonya's cartwheel). Attempting to step back and whiff-punish is a tad tricky if you're already within range of the roll when Kung Lao throws it out. In this case, though, you're talking about on block.
Actually, Carl and I were just discussing Kung Lao's roll last week at CEO and he said it was -4 on block. So as his spin and X-ray are six frames, his fastest follow-up will activate in ten. Skarlet can't beat the spin out unless she initiates her armored EX Blood Dash, and the X-ray will always win unless you block, so this is where it comes down to a read. If Lao attempts to follow with a jab string (traditionally variations of his 1 1 2 1 and 2 1), those can be ducked. Otherwise, your best bet is to just d1, d3, or maybe do 1 1 4 or 1 1 2 into her Blood Dash mind-games as Skarlet's standing 1 is ten frames.
I'm no Skarlet player, so just thinking of what I can off the top of my head.