Len Platt’s 2008 paper, “Madame Blavatsky and Theosophy in 'Finnegans Wake': An Annotated List” from the James Joyce Quarterly 45 (2), pp. 281-300, can now be accessed online. Platt writes
The central argument of my analysis of the Wake and theosophy in Joyce, Race and ‘Finnegans Wake’ is that Joyce understood theosophy not just as an insignificant absurdity that had a curious currency amongst Dublin’s Protestant intellectuals, but in a wider cultural context and as a symptomatic discourse of modernity. In this respect theosophy, like the race discourses with which it can be closely identified, demonstrated key qualities of the modern — the faddist instinct, the capacity for trickery and sensationalism and, perhaps above all for Joyce, the irrationality and the turn that contemporaneity had taken away from the egalitarian instincts of a once progressive order. The point being not to deny the importance of the Irish context — clearly the involvement of the Dublin crowd with theosophy was central to Joyce’s analysis of Irish revivalism as a faddist and conservative culture — but, rather, to recognise that Joyce’s engagement with theosophy was also part of a bigger and more complex engagement with modernity and the ‘enlightenment project’. It is against this wider backdrop that theosophy becomes of particular importance to the Wake.
Over fifty allusions to Blavatsky and theosophical concepts from Finnegan’s Wake are given and can be read here.