Well, wearing a black clerical collar was and still is a common practice of some members of the Setian Priesthood III*+ during formal Setian gatherings or when administering their duty as representatives of the Temple of Set in a public forum. Initiates of the Priesthood of Set take the Function(s) of their Degree very seriously, it is a sacred obligation to both themSelves and the Lord of Darkness.
Xeper.
/Adramelek\
I still question the need for this practice myself. I understand that ToS considers itself a serious religion (hell, I consider my religion serious), but borrowing the Christian clerical garments and just wearing a pendant or pin is a bit over the top. Now if you came out all heavy metal or dressed in a ceremonial robe with hood I get it since it makes sense we'd be wearing these clothes for our purposes. Both are expressions of Satan aesthetically, but I feel no bond with the typical minster apparel of other religions. I'm not just pinning the blame on ToS however -- CoS is very much a culprit of this as well.
If to exist we merely have to be an inversion or perversion of something we haven't much a leg to stand on. We should let these ideological, theological, and symbolic dinosaurs die the death they deserve and not seek to burn them into the minds of our enemies with our blasphemous travesties of their imagery. This makes as much sense to me as putting a pair of horns on a crucified Jesus and ceremoniously declaring that this is the son of Satan. It does nothing but incite the wroth of Q. T. Public.