I'd figure about how many you could do a hour. Depends on if your putting them in a hole of hope. Meaning dig a hole, put the tree in and hope for the best.
If thats the case it shouldn't take long for two guys to auger, set the tree and backfill. So I'd figure 6-10+ a hour.
Note: I've never planted trees like that but thats kinda what I'm thinking.