It is possible. You have to subclass QSpinBox and:

1.Override wheelEvent.
Here you will look at QWheelEvent::modifiers to see if SHIFT modifier is pressed.
If it is pressed then you can look at QWheelEvent::delta() and multiply it by 10 and add this value to the current spinbox value.

2.Override keyPressEvent.
Also, you look at QKeyEvent::modifiers() for the SHIFT modifier.
Next you test for the up/down arrows and act accordingly.

Regards