In any run of the tool, you can have only one process. If you want to try with a different process you have to give a different run.
"Primetime" from synopsys is an STA tool you can use for this task. It takes a netlist as an input to do the timing analysis.
You'll need a Liberty model with statistical variation tables and statistical static timing analysis. If you have the correct spice models you can extract the critical path and simulate with monte-carlo analysis for a few paths. Of course, this isn't practical for a large number of paths.