IAN is in my opinion just a simplification of procedures, instead of using different procedures for all kind of approaches one can use the same procedure for nearly every kind of approach. Instead of LNAV/VNAV or LOC/VNAV one simply uses the APProach mode same as on an ILS.
However there are still some differences, for example IAN does not allow dual channel approaches (quite correctly) and therefore has a green single channel indication instead of yellow, it creates an autocallout "AUTOPILOT" at 100ft RA to remind the pilots to take over manually and IAN cannot do RNP AR approaches. And of course one has to be careful which navaids are tuned since tuning an ILS can prevent IAN from doing its thing.
We use IAN since it was introduced by Boeing on the 737 and it is our standard procedure for non precision approaches, no idea if we needed another certification for it, however all crews received simulator training in its use, same as we did for CAT IIIb instead of CAT IIIa (both came for us at the same time).