No. Issue the MCO upgrade voucher as though you have confirmed upgrades all the way through. Tell Asiamiles that you will 'risk' it as long as they hold the waitlist for you right to day of departure. They cannot NOT say that all dates must be confirmed before they issue the voucher.

Waitlists can be tricky depending on load factors and dates. But generally, CX will clear the waitlist as short as a week to a couple of days prior departure.