it would be a little tricky, but it's possible.

you can download e-v2ray APP via your computer. ( https://apk.support/app/dev.epro.e_v2ray )

then transfer the apk file to a flash drive and connect it to the mi box and install the APK using a file manager like X-plore app.

Then, go to the V2ray tab on the buttom of the app. then copy and paste the config text here using Google TV Remote App.

Now, connect using the toggle icon on the home tab.

Enjoy