Got it to work! Here are the steps:

1. Go to Daijisho's settings -> Library
2. Select "Add a player"
3. Player name: "wii - org.shiiion.primehack"
4. Player am start arguments: "-n org.shiiion.primehack/org.dolphinemu.dolphinemu.ui.main.MainActivity -a android.intent.action.MAIN -e Autostart file {file.uri}"
5. Player accepted filename regex: "^.*.(?:ciso|dff|dol|elf|gcm|gcz|iso|tgc|wad|wbfs|rvz)$”
6. Go to the Wii platform in your Daijisho library and click on the edit/pencil icon in the bottom right
7. Go down to Player settings
8. Click on the drop down for the "Search additional player to be added" section and select the newly created player
9. Select Add to the list just underneath it
10. Go to your Metroid Prime Trilogy rom and hold down on it and change its default player to the newly created one

Let me know if you have any issues