Have you tried using the macro recorder to record what you currently do manually?
The recorded macro would undoubtedly need 'tuned-up' before assigning to the button but would be a great place to start.

Yes the Macro recorder would work, but its the fine tuning that is the road block.
The issue would be how to identify the selected line (highlighted) at the start, so the macro would know which material entry you wanted to run a route sheet on.

I'm not sure as to how I identify the selected/highlighted line within the macro so it knows what data to copy and export to the form.

I guess I could at least run the micro and then I would have everything but the identifying section at the beginning and work/"fine tune" from there...