If I run electrical current through the conductors in a magnetic shield, can It be used to shield stronger magnetic fields?
You would normally think of a magnetic shield as attenuating, that is multiplying by a number less than 1, an external field from one side (the agressor) to the other side (the victim). 

Regardless of whether a conductor is magnetic or not, running a current through it generates a magnetic field round it. This magnetic field adds to any others that are present in the region around the shield.

Therefore the action of an externally applied current in a shield is not the same as turning the shield on and off, or even modulating its attenuation behaviour in any way.

30GHz will remain unobtainable to most people, especially if approached like this.