I've run across their mention several times, but I can't find any information on them beyond they're a Boston based group that wants to restore Tír na nÓg to it's former state as Ireland. Does any further information exist, or is that all there is?

I'm curious about this as well. If anyone has any more info you'd have helped two people

Though the nice thing is, if there is no concrete evidence on them, we're free to play with them how we see fit!

I don't think they've ever been particularly fleshed out (not the way some of the gangs have, over the years). Moreso than a political group, they've been twisted over time into more of an anti-Elven metaracist group, IIRC. Not a whole lot else out there about 'em, really. I think they were peripheral characters in one of Kenson's novels.

This. I essentially wrote them up in my Minneapolis/St. Paul campaign, where they're prominent in predominantly Irish descended St. Paul, as essentially neo-Fenians. Some would be content to return Ireland to democracy whereas others simply hate all elves. Most are Catholic but some are Ulster Orangemen, and some segments accept non-elf metas while others are being courted by Humanis. But the main commonality being the cause of overthrowing the elven state apparatus in Ireland. But that was all entirely pulled out of my ass, really, the historical analogy to the Fenians being the main driver of the idea. Sort of a "here we go again" feeling for anyone who knows Irish history.