"Hippolytus was reconciled to the Church just before his matyrdom. He was not separated from the Church on his death.
I would think that Marcel Lefebvre would need to be reconciled with the Church prior to his death in order to be considered for Sainthood."
"Hippolytus of Rome was reconcilled with the Church BEFORE his martrydom. So when he died, he was not at the time considered excommunicated."
You are both correct re Hippolytus, however, Joan of Arc died excommunicate and was still raised to the altars.
There are also other instances of excommunication being lifted posthumously. Notably when Paul VI and Patriarch Athenagoras lifted the excommunications of Michael Caerularius and Cardinal Humbert after Vatican II.
If a future Papacy were suitably disposed, it would be quite possible for Lefebvre to be considered for Sainthood, although I think the chances are remote.
She was found not guilty of her accused crimes after her matrydom and her excommunication was declared null and had no effect; there was no excommunication.