In Dynamics GP 2013 (and Dynamics GP 2010) you can publish any SSRS report to the Dynamic GP home page. Here are the steps:
1) Build the report as you usually would. There are no tricks to the type of datasource or dataset.
2) The report has to be located in any of the "Charts and KPIs" folders that were created when you initially installed the Dynamics GP SSRS reports.
3) The report will be displayed as a really small image in GP unless you edit the report to have a custom page size:
a) The page size should be 4.15 in wide and 3.15 inches high.
b) The margins should be small (.0175 inches for a left and right margin gives you a 4 inch working area for your report)
c) Make sure you adjust the body of the report to fit inside this small area (4 inches)
If you get any error messages, here's a useful Microsoft kbase article:
http://support.microsoft.com/kb/2685089
Also see the attached setup/admin guide.