Package Manager is only a Graphical User Interface (GUI) that uses pisi to install software.
So if the (*.pisi) package is not in the software repository, it can not be installed through Package Manager nor pisi.
If that is the case the options are:
1. Request at package at here
and wait for things to happen.
2. Try to build the software from source code.
And to built "gnome-do" from source code look here