  In a recent Letter~[PRL \textbf{121}, 130404 (2018)], it was announced that
the spin-coherent-state POVM can be implemented via a nonadaptive continuous
isotropic measurement. In this article, the mathematical concepts used to prove
this are explained in greater depth. Also provided is the more general result
of how to implement a generalized-coherent-state POVM for any
finite-dimensional unitary representation of a Lie group.
