Download MikuShell.7z.

Open/Extract the .7z archive. You can use 7-Zip to do this.

Create a Skins folder in the root of your flashcart’s SD card.

Inside the 7z archive, you will find a folder called MikuShell.

From this folder, copy MikuShell.skn to the Skins folder on your SD.

[Optional] Some themes ship with a replacement start-up animation. If present, copy Splash.ani to /moonshl2/internal, replacing the existing file.

[Optional] Some themes also ship with replacement sound effects. If present, copy sndeff.dat to /moonshl2/internal, replacing the existing file.

Place the SD card back into your cart, and launch Moonshell 2.

In Moonshell 2, navigate to the Skins folder and press A on MikuShell.skn to apply the theme.