Rather than have a one-off, multi-day session, what about an on-going monthly or bi-monthly series? I am imagining something similar to a group that my wife is involved with (in a totally different field).
In her group, somebody gives a presentation online about once-a-month, each time a different person and a different topic. The topics target different levels of expertise, so some topics are general, while other topics are very specific. Interested parties tune in from around the world. The IT system used by my wife's group lets everybody see the presenter's slides, hear the presenter's voice, and hear voices of the audience members. After the presentation, the slides are available for download. Their system is provided by a large institution, but I suspect Google Hangouts (or similar) would work for Enzo's purposes.
If the Enzo group wants to do a similar presentation series, we probably need a volunteer or two to coordinate the series: find topics of interest, schedule speakers, moderate the presentations, etc. (In my wife's group, this role rotates annually.) I am willing to be one coordinator, but I think we should have two.