It looks like the way to do this is:
TORCH.NN.UTILS.PARAMETERS_TO_VECTOR 2
and
TORCH.NN.UTILS.VECTOR_TO_PARAMETERS 2
Specifically something like:
param_vec = th.nn.utils.parameters_to_vector(model.parameters().values())
param_vec += something # arbitrary operation
th.nn.utils.vector_to_parameters(param_vec, model.parameters().values())