Taking a look at this on the schematic, it is a bit deep in the engine and some parts removal will be needed. Unless you have performed repairs like this in the past with engine disassembly, then it would be best to let a repair shop tackle this job.
Cool, it looks like you can do this done and have done some research. When you open the distributor, you are going to measure the gap between the distributor shaft "G" signal notch and the camshaft position sensor. The notch looks more like a spike on the shaft. Face it towards the sensor and use a feeler guage to measure the gap. The specs are 0.2 - 0.4MM (0.008 - 0.016in) If it is not in spec then replace the distributor as the gap/sensor is not adjustable and they are really looking for play in th assembly.