  Since its beginnings, fission theory has asumed that low-energy induced
fission takes place through transition-state channels at the barrier tops.
Neverthess, up to now there is no microscopic theory applicable to those
conditions. We suggest that modern reaction theory is suitable for this
purpose, and propose a methodology based on a configuration-interaction
framework using the Generator Coordinate Method (GCM). Simple
reaction-theoretic models are constructed with the Gaussian Overlap
Approximation (GOA) to parameterize both the dynamics within the channels and
their incoherent couplings to states outside the barrier. The physical
characteristics of the channels examined here are their effective bandwidths
and the quality of the coupling to compound-nucleus states as measured by the
transmission factor $T$. We also investigate the spacing of GCM states with
respect to their degree of overlap. We find that a rather coarse mesh provides
an acceptable accuracy for estimating the bandwidths and transmission factors.
The common numerical stability problem in using the GCM is avoided due to the
choice of meshes and the finite bandwidths of the channels. The bandwidths of
the channels are largely controlled by the zero-point energy with respect to
the collective coordinate in the GCM configurations.
