You can not customize via any builtin user interface with xl2007.

You can however create a custom ribbon if you create the correct ribbonxml file and associated .rels files.
That site contains links to programs that will help you create/package all the files required.

If you want to do the processes manually then you will need to read the articles here.
http://msdn.microsoft.com/en-us/libr...ice.12%29.aspx