I am afraid you need to generate a representation of your system in P1 space group , specify all bonds yourself an disable GULP bond creation. I am still not sure how to set up cross- cell bonds in this way.
Related question - why do you need to specify bond type ? It play rule only for some force fields (UFF). Eg. gaff/gaff2 or Dreidin recognize forces from atom types and ignores bond orders … Even for uff I belive you can specify the forces manualy = ignore order and let GULP find them.