As of now, the only way to obtain the HGSS events is through changing the DS's DNS and Secondary servers in settings. You will also need a wifi router with a WEP security, for a greater chance of succession. It's not a guaranteed strategy, however it is an option besides Action Replay.
This video will guide you in doing so:
A second alternative using similar strategy, link is below, you have to set up a guest network. The video will give you all the steps.
Note: I trusted this process because it worked for me, but I can't 100% be sure if it works for everyone. Also, the feedback to the videos were drastically more positive than negative. Please let me know if I need to edit something or if you need more questions.