  We extend a recent method to shortcut the adiabatic following to internal
bosonic Josephson junctions in which the control parameter is the linear
coupling between the modes. The approach is based on the mapping between the
two-site Bose-Hubbard Hamiltonian and a 1D effective Schr\"odinger-like
equation, valid in the large $N$ (number of particles) limit. Our method can be
readily implemented in current internal bosonic Josephson junctions and it
improves substantially the production of spin-squeezing with respect to usually
employed linear rampings.
