Creating an Integrated Circuit Component in Altium
You will need to get the info from Maxim or use another IC if you really want to go that way. Yet I do not see how you will benefit from this. The only use-case for Altium's signal integrity part (which I have used in the past) is for transmission lines to determine proper signal termination. If you want to simulate the RF part, I guess you're probably better off with a different simulation tool.