The IMC course syllabus was written pre-GPS and hasn't, to my knowledge, been updated to incorporate GPS.
Having said that, if you were at a field e.g. Shoreham, that has a GPS approach and your aircraft is certified to fly GPS approaches, then it wouldn't be a 'modern' instructor that teaches an IMC course without incorporating some sort of training to enable you to fly the GPS approach.
Furthermore, GPS shouldn't be used as the primary means of navigation in non certified aircraft, and even if it is certified, I would still use cross cuts of radials and DME to confirm my position.
TJ