Huh, interesting that they specify you need the DN ability. Never noticed that.
Going by the Classic interpretation, any 'Mech may be declared as being outfitted with a neural interface at no cost to Battle Value (though in a campaign or other C-Bills-restricted matchup, there will be a C-Bill cost and maintenance check associated). It's simply a small, tonnage-less, space-less, BV-less factor of the cockpit on that specific unit. Looking at the list of units with the DN ability, looks like it refers instead to the Interface Cockpit used by Machina Domini, which is related to VDNI and EI. However, VDNI, Buffered VDNI, Prototype VDNI, and EI should not require any specific abilities.