Okay, so I've downloaded MasterController ver 134, and MasterControllerIntegration.
I put both of 'em in Documents\Electronic Arts\The Sims 3\Mods\Packages.
My version of The Sims 3 is 1.67.2 - from a retail disk.

When I fire up the game and hit Create A Household, bringing up the CAS menu...I can't get the Master Controller Menu to pop up. I've tried left-clicking the "..." button on the bottom left, right clicking it and clicking my scroll wheel. All of the above just bring up the standard menu that usually pops up when you left click that button.

Any help or advice would be greatly appreciated.

Yes, I'm afraid it doesn't quite work that way. MasterController is a Script Mod, the effects of which cannot take hold until gameplay is begun and the game clock starts moving forward smoothly. Even with the MC Integration module in place, if you launch the game and jump right into CAH, then you will still get EA's version of CAS and not the MC version. The way to get into MC's version would be to choose some already placed random sim to play for a few sim minutes, then retreat to Edit Town and get into CAH from there.

Oh, that makes sense. I'll try that right away and let you know how it goes.

I was a bit confused, since the YouTube videos I'd watched had people accessing MC through CAS immediately, but it does make sense, since they'd almost definitely put in playtime before installing the Nraas mods.