This forwarder let's you boot straight into GBARunner2 from your Hiyacfw system menu on your DSi.
Extract the .zip and transfer the "title" folder to your SD root.
This forwarder will run the gbarunner2_arm7dldi_dsi.nds file found in the _nds folder on your SD card.
You also need to have nds-bootstrap-hb.nds in your _nds folder. It comes with Twilightmenu++.
This was made using the makeforwarder.exe by edo9300 found here:
And GBARunner2 by Gericom found here:
Lastly nds-bootstrap here:
Disclaimer: You are using this at your own risk. You can always make your own forwarder yourself, easily.