Apotheosis in Tamriel is not limited to Talos, who was Tiber Septim before becoming one of the Nine. Indeed, Reman Cyrodiil, now called the Worldly God, was known before Ysmir: first as the greatest hero of the Akaviri Invasion of the First Era, and then as the ruler of the Second Empire. Under his dynasty, the Empire conquered all the kingdoms of Tamriel save for Morrowind…and it was Morrowind, and the Morag Tong, that led to his demise.
(Interestingly, Cyrodiil is not named for Reman as many believe. Instead, he took Cyrod, the ancient Ayleid name of the heartlands, as his surname.)
There is no obvious cult of Reman these days, but he was worshiped alongside Talos as a conquerer-god, and there is documentation to support this worship dating from as late as the first century of the Third Era. His rise to godhood stems from the heroic acts of his life – in addition to routing the Akaviri, who called him Dragonborn and swore their loyalty, Reman created the rites associated with ascension to Emperor and is credited with the creation of the Amulet of Kings. Scholars disagree on whether Reman held or was held by the Amulet, but it none can contest that the process of becoming Emperor is his.
When we look at the cultural god-kings of a prior civilization, it is useful to examine the qualities they embody. Reman, like so many other deified beings, was a hero who freed Cyrodiil from an invading force and brought prosperity to its people…from the Imperial point of view, anyway. This raises the question of similarity between practices for the cult of Reman and others – the archaic and classical hero-cults of Greece, for example, or the imperial cults of Rome – and I feel confident in saying that those who desire to worship Reman in such a way will do so with the Worldly God’s blessing. However, I prefer to think of the qualities not specifically mentioned that nevertheless would have been crucial to his success, and to base my approach to him on those very things.
As an example, consider that Reman is said to have convinced the Akaviri to support him in the founding of the Empire, and the actions documented by historians appear to bear that out. His powers of persuasion were significant, and the ability to sway others to my cause, to cause them to focus on what I want to accomplish, is something that I use in my work each day. It should be no wonder, then, that I look to Reman to strengthen my ability to persuade others that what I ask of them is both reasonable and desirable.
(For any who consider me cold for admitting these things, look to the nature of corporate America and understand that the channels I go through to implement processes and programs require this type of action. I am good at my job.)
For ideas on how to incorporate the worship of Reman into your personal practice, I recommend looking to modern worship of other deified mortals such as Heracles, or Gaius Julius Caesar.