This is going to be a hard mod to create, especially since you will need to have some talented voice actors (Both males and females) that can mimic the voices of the guards and everyone else.
I would add an additional following dialog to the guards. When you ask them to follow you they would respond back with "Anything for you my Emperor" or "I will protect you with my life, my Emperor"
If you're an Imperial supporting Emperor your new home would be in Solitude. You can have Legate Rikke/General Tullius to be your followers. This includes every other Legate and solider out there. If you side with the Stormcloaks you can still be an Emperor, but your home will be in Windhelm. Jarl Ulfric and Galmar can be recruited as your followers, and that includes officers and Stormcloak soldiers.
To become an Emperor you must finish the Dark Brotherhood questline. You must kill the current Emperor Titus Mede to become the next Emperor of Tamriel. After you kill him make it so that a courier from any available town comes running up to you with a letter from the Imperial city congratulating you of becoming the new Emperor. Yes I know it's rather sick and unbelievable to be rewarded of being Emperor right after you assassinated the current one., but that's how it goes.
You must be a thane of each hold to be given the maximum benefits.