Ya, you need 4wd HC at the moment for the last couple of kms, or at least HC. See recent trip reports for Athelney Pass/Salal Creek:
http://www.clubtread.com/sforum/topic.asp?TOPIC_ID=32371&SearchTerms=athelney
http://www.clubtread.com/sforum/topic.asp?TOPIC_ID=31794&SearchTerms=athelney
The descent has up to 40 degree slopes near the top. Right now it's pretty much bare ice due to the hot summer.
Here's the view to the summit of Athelstan from the top of Moonraker:
If you cross the mostly flat glacier and gain the west ridge (right skyline) at the toe, it's 3rd class to the top.