You really need a set of hands with longer tubes to make it work properly. Or you need to install taller canon pinion and the other assorted wheels to have room for the date wheel overlay.
Here's a post I made on another forum:
I was trying to explain to a member why it's next to impossible to use a standard 2893-2 ETA GMT movement in a Rolex rep. Actually any rep that doesn't use a standard ETA date wheel. I thought it may be of interest to some of the modders here so I will repost my reply to him:
I thought it would be easiest to explain the problem with a couple of pictures. Notice the GMT gears on the right of the movement and how high they sit. The brass gear is about dead even with the date wheel. That date wheel would normally have the numbers painted on it but they have been sanded down for when I previously put a DW overlay on it.
Now, on the other picture you will see how wide the Rolex DW overlay is, where it actually covers the gear. When you raise the overlay to where there is no conflict with either that wheel or the bottom of the dial, then you no longer have enough room to properly fit the GMT hand over the dial. Also, if you look at the GMT hand you'll see it has to be able to pass the dial markers, which are raised rather significantly on a Rolex dial. Remember, the GMT hand is the first to go on the dial. It would be much easier if it used the same configuration as Rolex with the GMT as the second hand in the stack.
So, as I said before, without installing the tallest set of canon pin, GMT wheel, etc that ETA makes, you will have an extremely difficult time getting it all to work properly.
This movement can be modified into a 2892-2 easily and works fine in a watch such as a Sub, SD, etc. It just requires removal of the GMT gear set.
Also the reason that 2836-2 is so much more popular for reps is that the canon pin set is already taller because of the day wheel, which is removed for the addition of the GMT module or for general use in watches that need an overlay.
Hope this helps explain it better.