How to reuse a standard menu item?

I'd like to reuse "Rename" refactoring menu item (command) for a language that's not supported in VS by default (F#). 

For F# source files this command is disabled. So, I need to solve two issues:

1. How to enable this command for *.fs, *.fsi, *.fsx files
2. Handle this command in our extension. 

Thanks!