As a follow up, in the last week or two I have used DL skyclubs in LAX, ATL(x2), ORD, JFK, SLC and RDU no issues at all. Staff at RDU had never seen a Velocity card before but after they looked it up I was allowed in no dramas.
Did this a while ago, go to the D gates first (ie clear TSA there) then when you want to go to your gate let TSA know at the checkpoint you came thorough first and they can swipe you through a secret door! It was actually really easy, the TSA there seem used to it
I travel that route quite often no problems at all.
The issue is that only one or two of the desks at T3 have a passport reader in them, which is what is required for the international checkin.
I've been told that when they move to T1 that this will no longer be an issue.
There is a trip report about this flight on a.net, and it says "This proceeded into a 30 minute conversation where I found out that the VA crew actually dead head on a Malaysian Airlines flight from SYD into KUL and vice versa."
That's interesting. She'll be on Air New Zealand from LAX - AKL in any case, as they are the only carrier that fly that route direct. You may find it is a codeshare on United, so her bags should be checked straight through from DSM.