The best way to do this in PPT IS to have all your macros in a ppam AddIn that has ribbon buttons to run them. This would be available to all presentations.
There's a learning curve but we have a simple example here
http://www.pptalchemy.co.uk/custom_UI.html
A clumsy workaround is to have all the macros in a file that you always have open and call them with a simple macro like this
Code:
Sub caller1
Application.Run "Master.pptm!macro1"
End Sub
Where the master file is master.pptm and the macro is macro1
I wouldn't do this.