Im not sure what you would use to change that R value.
You can make any device bi directional by using a bridge rectifier if your circuit can tolerate the voltage drop of two diodes, but you need a common point to reference the control signal unless maybe you use an opto isolator in conjunction with a transistor with bridge rectifier. Does this sound reasonable to you? If so i'll post details.
Actually it's not that complicated:
Connect opto (transistor output) to transistor, connect bridge rectifier DC side to transistor, connect AC side of bridge rectifier to current resistor terminals, make current resistor higher in value. As the opto is activated, it activates the transistor, the transistor shorts out the bridge with some resistance value, the bridge presents an AC resistance to the circuit just as it is now. You should still keep R in the circuit, just make it high enough to allow it to work in the circuit if the transistor connected to the opto turns off completely.