NXT.USBFunctions to choose and connect to NXT bricks connected through USB. So far, it works on Linux (users of other platforms, your help is welcome).
val bricks : unit -> device listbricks() returns the list of LEGO NXT bricks on the USB bus.
connect dev connect through USB to the brick device dev (given by Mindstorm.NXT.USB.bricks). See the section "How to connect the brick through USB" for more information.