You can use KeyRemap4MacBook:
<autogen>__PointingRelativeToScroll__ PointingButton::NONE, ModifierFlag::FN | ModifierFlag::NONE</autogen>
Replace ModifierFlag::FN with VK_CONTROL for either control. Keys that aren't modifier keys can be mapped to EXTRA1:
<autogen>__KeyToKey__ KeyCode::F1, KeyCode::VK_MODIFIER_EXTRA1</autogen> <autogen>__PointingRelativeToScroll__ PointingButton::NONE, ModifierFlag::EXTRA1</autogen>
Key Repeat > [Pointing Device] CursorMove to ScrollWheel Rate changes the scrolling speed.
See the source for the key code values and predefined settings.