So you want to add another link to the home screen of alfresco. All the links you see in the attached screen shot are added to the index.jsp page packaged as part of the alfresco.war file.
I am not aware of any other approach but If you can overlay the war file during the build, you should be able to add additional link to the index.jsp page and package it as part of alfresco.war along with all your custom modules.
I have highlighted all the links which you already see and added a custom link into it.
Here is the index.jsp file:
<%-- #%L Alfresco Repository WAR Community %% Copyright (C) 2005 - 2016 Alfresco Software Limited %% This file is part of the Alfresco software. If the software was purchased under a paid Alfresco license, the terms of the paid license agreement will prevail. Otherwise, the software is provided under the following open source license terms:
Alfresco is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
Alfresco is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License along with Alfresco. If not, see <http://www.gnu.org/licenses/>. #L% --%>