List of Shortcut keys in use

I made a userform to add comments and shortcut keys to subs I've written. Basicly, it is just a more userfriendly way to work with application.macrooptions. But to make sure, I do not overwrite an existing shortcut, either a standard Excel shortcut,or a shortcut previously assigned to another macro, I would like to create a function which checks if the shortcut is already assigned. Anyone a clue how to do this?

I searched the internet already, and all that I found that comes close is an addin of Ivan Moala, which creates a list of all the shortcuts in use. Only, the download page seems to have expired. As I found lots of reference to his Addin, I think that it must be a good addin, but also one of the only addins available?

any help will be highly appreciated.