[@mention:568484858377802720] As written in the Constitution (Section 5.2.1) "The Ratifiers may appoint an initial Lead Link". If any Lead Link, nothing is said re the decision process to choose/select such Lead Link. So back to your question, it's up to the Ratifiers to define such process, could be an integrative election, a vote, something else. Very often, what I have seen in my experience is as simple as they just choose the same decision process the usually use for other decision as a Partnership or Board.
It is sometimes weird to select only one Lead Link. One of our clients has a Board with 3 Business Partners who decide together re all important issues of the company. Adopting Holacracy meant for them that they had to select one Lead Link for the GCC when they would have naturally preferred to get 3. I'm confident that version 5 of the Constitution would allow for such an option.