Custom equivalent lateral force procedure and seismic definition/custom model response in Staadpro CE

I am tasked with designing a steel support structure in Staadpro connect edition. As part of the design, I need to conduct a seismic analysis of the frame. The steel structure is 12 m high and needs to be designed according to the New Zealand seismic standard, NZS 1170.5. Since Staadpro does not support 1170.5, I will have to do a custom seismic load generation within the software. I would like to conduct Two types of analysis; the equivalent lateral force procedure/a modal response spectrum analysis. For both of these instances 1170.5 is not covered. Moreover, there is not an alternative option to define a custom procedure under the seismic definition in the loadings tab.

1) What is the best way of going about this problem? I would be more comfortable conducting two different type of analysis for comparison than focusing on one type only. However, if I’m forced to only make use of the model spectrum analysis, I would gladly do so as long as I can confirm that the procedure that I implement is a correct reflection of the analytical problem.
2) What is the closest related loading code to NZS1170.5 implemented by Staadpro

3)Finally, the structure needs to be designed to NZS340 and will be designed as a nominally ductile structure. Can you refer me to any resources where this particular standard has been implemented as an example in Staadpro.