The command is like this:
/// Highlight a button on one of the controllers. Syntax:
///
/// highlightcontrollerbutton [left|right] [button] [strength] [frequency]
///
/// e.g.
///
/// highlightcontrollerbutton left hub 0.8 2
///
/// available buttons are:
///
/// pistoltrigger
/// grip
/// thumbstick
/// button1
/// button2
/// hub
/// Use strength zero to turn off the highlight.