networking the low level stuff

is it possible to manipulate when packets are sent and what is sent in them? i want to use unity for a research project but i need to be able to specify when to send packets over the network and possibly what i send over the network.

If you use C# scripts, you have the full functionality of its libraries. Of course you can send whatever you want whenever you want, using the protocol you want (for example, google the C# TcpClient class). Then this turns more into a C# question than a Unity question. Not sure about network libraries in UnityScript and Boo.