Uhh, negative. There is a big difference between "Can these 6 X-men eventually kill a million uruk's?" and "Can they defend helm's deep?"
Eventually some Uruk's will make it into helms deep's walls, and at that point, the game is over. The failed to defend Helm's Deep. See the difference?
Now, could they take that many Uruks? Probably. They couldn't do ANYTHING to colossus. Wolverine would eventually be put down, but Kitty could just phase through them, ripping their hearts from their body as she does. Ice man could ice up and be invulnerable, and then take them down with relative ease. Beast would eventually be in the same boat as wolverine. Storm...as long as she stays out of the way, could wreak havok.
Hmm..I would say Colossus could do it alone. Kitty could do it alone. Ice man may be able to. Storm could as long as they had something to distract them. Eventually one of their arrows may get through, considering they'll have so many chances. Wolverine and Beast could take tons of them, but eventually would still be put down.