Ikelite zoom ring assembly

I just got the Ikelite housing for my Canon 5D. I have the f4/L 17-40mm zoom, 8" dome port and the plastic zoom ring that comes with the housing. After some experimentation, I finally figured out that the zoom ring gears on the outside of the housing, so it's held between the housing and the dome port. However, the zoom ring doesn't fit over the end of the 17-40mm lens. So this is the assembly I figured out:

1. Assemble camera in housing, without lens

2. Put zoom ring on lens

3. Attach lens to camera

4. Place port on housing

To dissasemble, I do this in reverse, only I need a pencil to press the lens release on the camera so I can get the lens off.

Am I missing something here? I hate the concept of taking the lens off while it's still in the housing. When I switch lenses on a boat, I don't want a drop of water getting to the inside of the camera from the housing.

Thanks for your help.

Yes, that's correct.

However, you can use the DOF-Preview knob on the left side of the housing (viewing from back) to hit the lens release button.

That's a good trick, thanks. I guess I'll just have to use a lot of towels.