Two resources; one from Canada in PDF format and from their explanation:
The first step in understanding how to engage with these at-risk men is to understand how they communicate and share their worldview.Incels have developed their own coded and highly specialised language, which they use to communicate in online forums and spread their ideology. This guide aims to demystify the jargon and symbols they employ; provide definitions and context; and demonstrate how language choices fit into a wider system of belief.
Link:http://moonshotcve.com/incels-symbols-and-terminology/

Then a webinar from GWU, with the following SME:
The panelists, who discussed their research on the topic, were: Bruce Hoffman, the Shelby Cullom and Kathryn W. Davis Senior Fellow for Counterterrorism and Homeland Security at the Council on Foreign Relations and a professor at Georgetown University's Security Studies Program; Renske van der Veer, Director of the International Centre for Counter-Terrorism (ICCT) - The Hague; and Jacob Ware, Research associate at the Council on Foreign Relations.
Link:https://www.youtube.com/watch?v=2QessrnaeG8