In order to waitlist, you just need to have any itinerary ticketed as a saver reward, in the same region. It can be on partners and it can be confirmed in a lower class of service and it can have a connection. I'm not even sure if it needs to be the same origin/destination.

I think that the award may need to be issued as a Business class award in order to stand by for Business, even if you're only confirmed in Coach. At least it used to be that way. I'm not sure if you can book a coach award and then stand by for Business and expect them to take the additional miles out.

Of course if you have a business award confirmed in coach and you never clear into Business, they'll refund the mileage differential after the fact.

Definitely look at the "Plan B" thread. Keep in mind that requires being booked in coach on the exact flight you want to get in Business. Normally the waitlist expires at T-24. If you're booked on the same flight in coach, then you can still get on the upgrade standby list at the airport, and you should have higher priority than customers trying to upgrade, since you are a "paid" business class passenger displaced into coach. Full details in the Plan B thread - particularly how to approach the agents about this, because generally they shoo anyone away who asks about "upgrades" at the gate.