While you can connect the simulator to a real BES, you cannot fully emulate the environment. With a real device, the device connects thru the carrier to the RIM relay and your BES. However, with a simulator, you cannot connect to the relay and/or carrier.

For this reason, there is no need to change the PIN #. However, if you want to, you can do this via Edit - Preferences - Simulator. Change the Profile to something other than the default and edit the command line on the Advanced tab.