Apple - Mouse Wheel Emulation on Mac

You can use KeyRemap4MacBook.

Scroll by moving the pointer while holding the secondary button:

<autogen>__PointingRelativeToScroll__ PointingButton::RIGHT</autogen>

Scroll by moving the the pointer while holding F1:

<autogen>__KeyToKey__ KeyCode::F1, KeyCode::VK_MODIFIER_EXTRA1</autogen>
<autogen>__PointingRelativeToScroll__ PointingButton::NONE, ModifierFlag::EXTRA1</autogen>

Scroll with F1 and F2:

<autogen>__KeyToKey__ KeyCode::F1, KeyCode::VK_MOUSEKEY_SCROLL_UP</autogen>
<autogen>__KeyToKey__ KeyCode::F2, KeyCode::VK_MOUSEKEY_SCROLL_DOWN</autogen>

Scroll by moving the pointer while holding the primary and secondary buttons:

<autogen>__SimultaneousKeyPresses__ PointingButton::LEFT, PointingButton::RIGHT,
KeyCode::VK_CONFIG_SYNC_KEYDOWNUP_notsave_pointing_relative_to_scroll</autogen>

See the source for the key code values and predefined settings.

You can map scrolling to pressing a key and moving the cursor from the GUI!

Here, I map the scrollwheel action to pressing the Fn key and moving the cursor. Notice the nice option that enables this behavior for both horizontal and vertical scrolling.

By the way, KeyRemap4MacBook is now called Karabiner. https://pqrs.org/osx/karabiner/