John Doyle
Ansys Employee

I assume by "Norton-Bailey"  you mean an expression of the following form:  

In Ansys, you can curve fit the Time Hardening Creep expression, with C4 set to zero. 

You would have to convert your displacment values to an equivalent strain (=delta_L/L).

Please refer to Chapters 4 and 6 of the MAPDL Material Reference Manual or more details.