For those who are still looking for an answer to that old but still valid question.
In AssetDataGatherer there is a flag that controls whether the dependencies must be gathered :
bGatherDependsData = (GIsEditor && !FParse::Param( FCommandLine::Get(), TEXT("NoDependsGathering") )) || FParse::Param(FCommandLine::Get(),TEXT("ForceDependsGathering")); if you are outside of the editor, adding the extra -ForceDependsGathering on the command line will do the trick.