there was a really interesting article on cadred about it. Basically, they don't do what they suggest they do.
To make sure you don't have acceleration, make sure the "Enhance Pointer Precision" box is unchecked in windows control panel.
Then, dump this into your Autoexec
//--------------------------
//MOUSE SENS
//--------------------------
m_customaccel "0"
m_filter "0"
It removes acceleration in tf2