define a keybinding for "find next alternate definition of last tag specified"

[Burkhard Schultheis]

I want to have a single keystroke for the keystroke sequence C-u m-. 
(find next alternate definition of last tag specified). as far as I see 
there is no command associated with this action.

How can I define a global key in my .emacs file for this action?

Thank you in advance!

Regards
Burkhard