Replace the default WinPE wallpaper image in the boot image or mounted WIM
Edit `winpeshl.ini` to launch a custom shell or startup script
Modify `startnet.cmd` to run commands that set the desired background behavior
Use a custom `background.bmp` or `background.jpg` placed in the appropriate WinPE resources folder
Update `winpe.wim` with your custom image files using DISM
Add a custom theme or shell replacement if using a graphical WinPE environment
Change the background color in the custom shell application
Set registry values for the shell or UI application if supported by your WinPE build
Rebuild and redeploy the WinPE boot media after making changes