Infinite Flight has support for Instrument Landing System for runways that are equipped in real life.
First, having support for ILS doesn't mean that the airplane can land by itself, it means that the airplane is equipped with a receiver that shows the position of the airplane in relation to the glideslope/localizer path to the runway.
For automated landings (or approach at least), the autopilot has to feature the APPR mode which we have no support for at this point. (it will come later)
Infinite Flight doesn't yet have a way to tune to frequencies, instead, we have a system that automatically tunes to the right frequency based on where the airplane is.
The ILS indicator is located in the center of the compass (in the HUD).
For more information about the use of the ILS, check the wikipedia article or google it :) http://en.wikipedia.org/wiki/Instrument_landing_system