You can find this in the reference under PlacedSymbol - there is example code when you click on one of the constructors:
http://scriptographer.org/reference/ai/placedsymbol/

This should work, let me know if it doesn't:

var symbol = document.symbols['Name of the Symbol']; 
var placedSymbol = new PlacedSymbol(symbol, new Point(100, 100));

Awesome! Thanks! That's exactly what I was looking for. I'll try to study the reference guide more attentively in future.

Squis