How can i do viaversion in bungeecord?

You can't, you have to put it inside each spigot server.

 

Read the plugin description next time

 

You can put it on bungee just make sure your on the latest version of bungeecord

 

You would need a Resource like https://www.spigotmc.org/resources/protocolsupportbungee.8733/

Usage notice:
You still need ProtocolSupport installed on all backend servers.