Current limiter of negative/positive pulse
Generic answer for the question- if your unipolar regulator circuit blocks reverse voltage, then put two complementary circuits in parallel. If it conducts in reverse then put two complementary circuits in series or two unipolar in series back-to-back. 

For example, if you were to use current regulator diodes (which are basically a JFET and resistor) they conduct in the reverse direction so you could do this: 



CLDs are fairly rare and relatively expensive these days, so it probably wouldn't be your preferred solution- just an example since you have a circuit in mind.