Customize the wheelPanning behaviour.

[0x0wen]

The wheelPanning feature is really a life saver, but I need to add some customized behaviour to it.
How do i do these things:

1. Adjust the sensitivity for the panning (the wheel's step/smooth step doesn't work for this)
2. Enable horizontal panning using the shift key and wheel

The documentation doesn't provide detailed information about the wheelPanning feature, perhaps because it's not added by the creator, but it would be nice to have it on the docs.