how to add softsim to an existing project like nrf_cloud_multi_service

Hi,

We recently managed to get the onomondo softsim working on a dev kit, we used the sample code provided by onomodo to do this. Now we want to add the softsim to the nrf_cloud_multi_service sample. What are the changes that we need to make on this sample inorder for it to work with a softsim.