Mod installation is very simple. Just need to extract and copy some files around.
1. Setup Jet Island with IPA
IPA is short for Illusion Plugin Architecture, it let's you inject code into Unity games.
If you've already setup IPA you can skip this step.
Note: This is a patched version of IPA that fixes this issue. Versions of IPA higher than 3.4.1 most likely will not require this.
Extract the IPA .zip to the game folder
For Steam Version: Steam\steamapps\common\Jet Island\
For Oculus Version: Oculus\Software\Software\master-indie-jet-island\
Drag JetIsland.exe onto IPA.exe
2. Installing the Mod
Now that IPA is setup, it's time to install the mod.
Copy the mods .dll to the Plugins folder
Some mods may require additional setup
Refer to the mod itself, if there is any additional setup required.