Nope, not from INSIDE at all.
But before you decide to "skip" the Dinner -or- Wishes... consider that Wishes is performed at 10pm that night (6/09/06) so I recommend you show up at leat 30 minutes EARLY for your Liberty Tree ADR ressie and they may be able to seat you sooner.
That way, you'll be finished eating in time to see the show outside.
Closest spot:
You'd need to go outside and walk directly across the pavement to near the Steamboat loading dock area.
Find a spot where you can look through the opening between the buildings to the Hub (the loop of street in front of the castle) and you'll see pretty well from there.