In the US, if you're flying a Localizer Approach, whether you have an RNAV/GPS system or not, an FMS system or not, you are required to monitor and steer the raw electronic localizer.
If you desire steering commands, or an A/P coupled LOC approach, some Airbus FCUs (assume the A300 does from previous posters) have a LOC button and the Boeing MCP has a VOR/LOC button for this purpose. You may use whatever vertical flight path tricks are in your 'kit', i.e. VNAV, APP DES/P.DES, VS, FPA, D & D, or random thrashing manual flight (
) as long as you track the raw LOC
and adhere to any altitude constraints on the depicted procedure with whatever 'sophisticated' or primitive cowboy charting information you have in 'some countries'.....particularly including the MDA.
My manuals are FAA approved and they approved LOC approaches in LNAV/VNAV. If its good enough to wind through fjords in SE Alaska, it should be good enough wherever there's WGS-84. In China, I'd have second thoughts.
But, of course this is in a B73NG, not an A306.