Oh well, if one has IAN it is absolutely possible to fly RNP approaches to minimum "raw" data, but then, it is a glideslope and loc pointer on the PFD behaving exactly like the real thing, or GLS for that matter. No need to activate VNAV or APProach mode for that, simply activate the relevant approach in the FMC and that is all that is needed to get the pseudo-ILS indication. In our operation we did only need flight director or approach mode for anything below RNP 0.3.