This is not exactly great, but suppose you have a selection, you can do Edit > Other > Enumerate, make the start number the first line number, and enumerate decimal numbers counting up by one. Copy, then Undo. If you record a macro for this, you can change the call to "enumerate()" to replace the start line number with p_RLine. For example (assuming you made the selection from bottom-up):
_macro('R',1);
enumerate(" "p_RLine" 1 6",null,null,'0');
last_event(name2event('C_C'));copy_to_clipboard();
undo();
undo();