[Dan Walker]

   I have used the method that Fred uses, but instead of spray adhesive I have taken titebond and mixed it with a little water .. I take this watered down glue and inject it into the slit with a syringe.
  I need a larger syringe because of the thickness of the glue.
 Also as Fred suggested,  tape each side of the slit so when the glue squishes out it won't glue everything else around it. .Place a flat board on the slit with a HEAVEY weight on top of it. [or clamp the board ,if possible] Tape the flat board on the bottom with masking tape so the board won't get glued down.
   I do this before I do any stripping so any residue glue won't get on the top  of the veneer, it may get on the old lacquer [but that will be stripped of later] 
As others have said there is no sure fire way and sometimes it works very good , and other times it does not work so good.