without removing the water pump in my 300e. Yes, I cut the hose and installed the new one through the gap. The secret is buying the hose from the dealer as it is more flexible than after market. You will need lubrication and a lot of patience but, it will get in there. Worse comes to worse, you will need to remove the water pump. By the way, if you need to cut the pipe, make sure it is on the water pump side.
Good luck!