Overriding class without compiling engine

There’s currently a bug in UMG (detailed here) where scroll bars aren’t draggable. The only thing that needs to happen is for a single bool function to be added to SScrollBar. I’ve implemented minor fixes like this in the past by compiling a custom version of the editor, but it’s a pretty painful process that I’d like to avoid if possible.

Is there any way I could swap out SScrollBar with a custom class from my project code? I’ve seen that this is possible with some Engine classes by putting an entry in a config file, but I’ve yet to see any evidence that this is possible for arbitrary classes.