Hello,
I've been looking around but I couldn't find this, in general it seems probably difficult to remap mouse scrolling wheel or trackpad scrolling to something else. Or maybe the answer is buried somewhere in the forum and I couldn't find it 
The application Draw.io use mouse/trackpad scrolling + Opt key modifier to zoom in and out. In many other similar apps the key modifier for similar operations is cmd and I got accustomed to it, so I simply wanted to create this simple remapping:
When in certain applications (in this case Draw.io) if I scroll up/down with the mouse or trackpad + OPT key is pressed -> remap the modifier to CMD and still capture the scroll direction.
Is this possible? I've had the impression that capturing scroll event is a bit more difficult than other events?