0. You must be on Luma3DS 7.0+.
1. Hold SELECT while booting your 3DS to open the Luma Configuration menu.
2. Enable "Enable Game Patching".
3. Copy the contents of this file to the root of your 3DS SD Card.
4. Launch Alpha Sapphire normally, it will be modified into Star Sapphire. You can tell based on the Title Screen and Brendan/May's outfit.
These were all that was in the instructions.txt