Hi Daniel,
you are right: People answering here have little or no experience with SALV object model.
Well, I can't give you complete code, just some hints:
It depends if you use the 'full screen' display or display within container. For fill screen, yo have methods to set your (modified) screen status, for container you must register the toolbar event to add a button dynamically.
You have to register events for toolbar click. Then get the current row to build you popup table, then create a new SALV factory object and use display method with popup parameters (from/to/x/y) filled.
That's it.
Regards
Clemens