  We show that gap-acoustic solitons, i.e., optical gap solitons with
electrostrictive coupling to sound modes, can be produced with velocities down
to less than 2.5% of the speed of light using a fiber Bragg grating that is
linearly coupled to a non-Bragg fiber over a finite domain. Forward- and
backward-moving light pulses in the non-Bragg fiber that reach the coupling
region simultaneously couple into the Bragg fiber and form a moving soliton,
which then propagates beyond the coupling region.
