In the RF Blockset 2.4 (R2009a) there no way to model an kind of switch in the RF Blockset. One of the reasons is that there is currently no way to model an RF network with more than 2 ports.
A possible workaround would be to model a switch in the RF Toolbox, and cascade the s-parameters using the CASCADESPARAMS command. This will allow you to model networks with more than 2 ports. For an in depth example for how this can be done, see the documentation page of the CASCADESPARAMS command.
