I've completed the main quest through the end of Sixth House Base, and I've killed Hanarai Assutlanipal, Dagoth Hlevul, Dagoth Fovon, and Dagoth Draven, but none of the 15 sleepers will talk to me about "Sixth House" to let me get their reputation.
Checking into Morrowind_ob.esm with the CS, I see that (as far as I can tell) nothing is scripted to happen on the deaths of any of the four related to the Sleepers quest, and the "Sixth House" dialog topics all require fbmwMQ14 "Destroy Daguth Ur" to be at stage 50 or greater.
In other words, that entire "wake the sleepers before beating the game" (as described in detail by the UESPwiki) is entirely omitted from Morroblivion.
(EDIT with additional info): I also did a full-text search of the entire Morrowind_ob.esm file, and nowhere in it can I find anything that does 'SetStage fbmwA1Sleepers 1', but rather, the only thing that starts the quest is beating the game which sets the stage to 10. I had to manually SetStage to 1 to get this to work, after manually removing the quest requirements with TES4Edit (since I already fulfill the requirements in my save).
What actually needs to happen is the script to have some sort of variable that is set upon beating the game or upon clearing the sixth-house base, and the dialogue predicated on that.