I'm not entirely certain that information is available in Lua. The information printed by the console command
ren_ShowNetworkStats is not available, for example. That is directly printed on screen by the engine.
If I can access the data it shouldn't be that difficult. If not, maybe the ICE adapter is capable of at least generating the information. Showing it in the client is another story .
BlackYps made a similar suggestion - it is coming!