I want to use two XM430-W350s in dual mode and try current control mode. But the manual says the slave motor uses a PWM signal—is this possible?
Yes, this is possible, you can do this by assigning an alternate id to the secondary actuator via Secondary(shadow) ID [Address 12].
With torque off, make sure both DYNAMIXEL are set to current mode, and then assign the secondary(shadow) ID to the ID you want it to follow.