...but in this instance you can select the ILS - and use it as an overlay. LNAV VNAV should then work, with appropriate raw data and profile height checks.
I dont see why the honeywell FMC cant be as flexible as the smiths FMC.
Smiths you can just build rwy extension and waypoint on waypoint, plug some altitudes in and watch LNAV VNAV fly it for you.