Does one have to have an empowerment in order to practice Mipham's Shower of Blessings? I remember, in our temple, we frequently performed the SoB Tsok, and participation was open to everyone. Are there parts of the sadhana (e.g. the daily non-Tsok practice) that can only be practiced by those who have the appropriate wangkur?
I think it would only help to get a Guru Rinpoche wang, but I never got the impression a wang was necessary for that practice. There is no self-visualization, etc. Certainly the lung for the seven-line-prayer would be important though, as this is the heart of the sadhana. And, it would help to have a Guru, i.e., to have had some kind of wang, or transmission before, since the essence is Guru Yoga. If you used to practice it all the time at your temple, I am guessing you have a Guru, and are familiar with the practice. That should be enough to practice it on your own. It is all about relating to the blessings of Guru Rinpoche, and your own Guru as Guru Rinpoche, etc. etc. If you feel a resonance to that, if you have some devotion, this practice is quite powerful.