Overdose - Methadone

[Dole654]

There seems to be quite a bit of discussion on methadone of late. After reviewing most of the posts and pdfs, I am still left with a question. There isn't much relating to methadone dosages, specifically in the case of overdose. I realize there are many, many variables involved, and the pharmacology / pharmcokinetics of methadone are quite bizarre, but does anyone have any comments?

To spur discussion:
Any guess at a lethal dose for an opiate naive user?
When these documents talk about overdose after 3 or so days of mmt, are they talking about 20mg or 60mg daily (on average)?

[Dole654]

Do nausea and vomiting occur at pre-lethal toxicity levels (one would assume so...)? Can they be used to determine a safe dosage (ie if swim didnt vomit at 25mg, he's probably ok to take 30mg)?