You can use the "PARAMS:" statement directly after the subckt header to identify parameters for use in a model. See below for an example on 2 different ESR capacitor models that allow you to set parameters up. The parameters can be used with { param1 } to identify them within the subcircuit - the expressions using the parameters are evaluated right before the simulation occurs.
Once set, you only need to adjust the parameters once (you'll still need to press the 'Edit Model') but you won't need to do any special calculations internal to the model.
This is what a model looks like with an included 'PARAMS' statement when you click on the edit button...