Hi @levelbest,
There may be a way to create something like this all in KM with a custom HTML prompt, but a solution that makes it easy to edit text from any app in a text editor of your choice has been around for a while. I recommend starting here: QuickCursor replacement
Hopefully the macro posted there, or one of the others found in the posts it links to, will get the job done for you, but if not, feel free to report back.