Get some time to get in touch with an agent that can help you looking for and maybe printing how the airlines deals with jumpseaters from other airlines. Back when I was an agent in an international station a pilot from a regional flew donw to our station and was trying to fly back, he had with him the regulations for the 4 mainlines that operated out of our station. Said which airlines allowed international JS and how to process them. Obviously you will need some good smiles and great attitude..and some people cant pull that off!