Modifying a Matlab Simulink Model

I have a Matlab Simulink Model. Here one of the parameter is constant (say one of the temperature) which is connected to several simulink components. However, I would like to change this temperature as a time dependent properties, where it will be updated at different times. This new time dependent temperature data can be read from an excel file. Everything is exist in the model and I would like to make this one one change for this single parameter.