"Basically seperating Formant from base, and the ability to set a Freq range on the base will do that simple effect."
There you have it. Now find the relevant parameters and settings.
To put it straight, what it says is that you use a pitch-shifting plug-in that can perform pitch-shifting separately to the entire sound and just its formant parts: UltraPitch and PurePitch have such feature among others. Shifting formants is simply known as "formant shift" in some contexts. It will definitely end up to the direction of that voice in the trailer. Having not used the plug-ins mentioned, I'm not sure how they operate regarding this (should be straightforward to find out though), but it sounds like the key is to find a correct balance (mix and the ratio of pitches) between the shifted formant part and the unprocessed base pitch part (which although may be shifted as well), so that the speech sounds intact. If you follow the tip precisely, it suggests to adjust the base pitch only, but not the formant part, but that sounds like it's rather specific to those plug-ins then (i.e. the formant part will stay at base pitch, but the base part will get shifted, leading to some some strange phasing I assume). Or if you read it very carefully it says to limit the range of the base pitch, which I assume means that the base part gets limited in its pitch range while the formant part retains the natural pitch variation (i.e. is left untouched), which again should be something specific to those plug-ins.
The best/only approach is to study those plug-ins throughouly to find out what the parameters do. And then find settings that work.