I know that this is a difficult question.
The Logitech M525 is a simple mouse with two buttons and a wheel. Backward/forward buttons are implemented as left/right tilt of the wheel. There is no special buttons or features on this mouse. Logitech V470 is also very similar to M525 other than it is a Bluetooth mouse.
On Windows/Linux, backward/forward mouse buttons are supported natively, so those buttons of M470/M525 work out of the box without any special driver or program. OS X, on the other hand, does not support them natively. It seems Logitech Control Center has extra modules to receive the backward/forward button inputs from hardware and send back/forward messages to programs.
The problem is that the Logitech Control Center supports V470 but not M525. So, the backward/forward buttons of V470 works but not those of M525. Personally I do not find any technical justification for this. To my contemplation, that should be very easy for Logitech to support backward/forward buttons, because all the logic is in the Logitech Control Center itself, not in the hardware. But for some reason, Logitech has refused to support M525 on OS X.
I guess the hardware signal code for backward/forward from M525 must be the same as V470, because they work without drivers on Windows. So, if I can deceive Logitech Control Center so that it thinks my M525 to be a V470 (or any similar model that is supported by it), the backwards/forwards buttons should work.
Is this impossible? Of is there any way to achieve this?
PS: I tried third-party general mouse backward/forward enablers, and they did not work well.