I am unaware of them explaining how individual members of the 144,000 are able to assist the GB in producing doctrine. Rather, they are quite direct, particularly since 2009, in showing that the GB act on behalf of the Slave.
"Would all anointed Christians “shine”? In a sense, yes, for all Christians would participate in preaching, in disciple making, and in building one another up at meetings. Anointed ones would set the example. (Zech. 8:23) In addition to this, however, deep things were to be revealed during the time of the end. The very prophecy Daniel recorded was “sealed up” until that time. (Dan. 12:9) How and through whom would the spirit search into these deep things? When the time comes to clarify a spiritual matter in our day, holy spirit helps responsible representatives of “the faithful and discreet slave” at world headquarters to discern deep truths that were not previously understood. (Matt. 24:45; 1 Cor. 2:13) The Governing Body as a whole considers adjusted explanations. (Acts 15:6) What they learn, they publish for the benefit of all."
Watchtower 2010 Jul 15 pp.22,23
"However, Christians who have truly received this anointing do not demand special attention. They do not believe that their being of the anointed gives them special insights beyond what even some experienced members of the "great crowd" may have." p.23
"Today, the Governing Body represents the faithful and discreet slave class." Image on p.23
"Similarly, today a limited number of anointed men have the responsibility of representing the slave class. They make up the Governing Body of Jehovah's Witnesses." p.24
Watchtower 2009 June 15 pp.23,24
"The anointed and their other sheep companions recognize that by following the lead of the modern-day Governing Body, they are in fact following their Leader, Christ."
Watchtower 2010 Sep 15 p.23
Most articles are written by members of the Other Sheep and simply authorised by the Governing Body.
"4. Those used as writers must be dedicated, baptized brothers or sisters in good standing with their local congregations and who have writing ability. They should be exemplary, modest, not inclined to talk loosely to others about their writing activity. ... 5. PREPARING MATERIAL: The subjects on which articles may be written are quite varied. Some articles will deal with spiritual matters, and these should be written by brothers."
Branch Organization Manual p.24-1 Paragraph 4