Adding code to engine’s main loop is quite easy.
You need to subclass a GameEngine and reference it in your DefaultEngine.ini file like this:
[/Script/Engine.Engine]
GameEngine=/Script/Sample.SampleGameEngine
From there you can define your own Tick function.
But why would you do that? I’m not networking expert, but it seems that unreal’s net code can easily support that protocol. The easiest solution would be to use RPCs to communicate incoming commitments and actual commands.