It is not currently possible to do the tranformed version of the EQUIV
model in JAGS, since it uses a symmetric order constraint, namely

tau[1] ~ dgamma(0.001, 0.001) I(tau[3],);
tau[3] ~ dgamma(0.001, 0.001) I(,tau[1]);

This construction is not allowed in JAGS because it creates a directed
cycle in the model.