The ability to scale the Simulink Scope y-axis on a Mac using a one-button mouse is not available in Simulink.
To work around this issue, you can export your data to MATLAB and use the SIMPLOT command to plot your data from MATLAB. This will generate a MATLAB figure that will allow you to change the figure properties. For more information, type 'help simplot' at the MATLAB command window prompt.
If you need to manipulate the Scope window for simulation, you can use the following snippet of code:
shh = get(0,'ShowHiddenHandles');
set(0,'ShowHiddenHandles','On');
set(gca, 'Ylim', [min max])
set(0,'ShowHiddenHandles',shh);
where min and max are the minimum and maximum values in the Y-axis.
NOTE: Simulink does not support manipulating graphics properties using the Scope or Signal Viewer handle. When manipulating any graphics properties, do not change or alter the structure of the scope. For example, you should not delete any of the graphical objects (text, axes, menus, etc) in the scope as this could lead to unstable behavior.
Also, depending on the X-windows system that you are using, there may be a preference that allows you to configure a keystroke/click combination that emulates right-clicking. For example, you can browse to "X11->Preferences->Input" and select the check box on top. This allows the "option+click" and "command+click" to emulate the middle and right mouse buttons respectively.
