It can be done using the initial content system. You should use a custom file though not the one included. There is a config setting indicated in the documentation to ignore the file we include this way you can use only your custom config file. You will have to develop your file by reading the documentation and trying it on your local machine with creating new sites, then when you have it working as you would like then try it on your production site. I use this feature myself to populate the mojoPortal demo site.
Best,
Joe