You are correct 1 dyne =10^{-5} Newton. You can't raise something with units to a fractional power, so you must be intended to measure the shear stress in dyne/cm^2 and raise the value to the power $0.58$. The shear stress must really be divided by a standard value of 1 dyne/cm^2, and you should consider that term dimensionless. For dimensional analysis we can then ignore that term.
Now match up the units in the rest of the equation to find the units of K. To convert to $\mu g$, you use the fact that 1 mg=1000 $\mu$g, so terms with mg in the numerator get multiplied by $1000$. You also need to convert days to hours, so where you see day you should put 24 hours.