List,
I'm not sure of the make of the original posters saddle, but for the Ideale and for Brooks saddles I've found this to work. Most squeaking Brooks type saddles is the result of the leather rubbing against the end of the canticle. What I've done in the past was to gentlypry the leather away from the canticle and insert a small ( 1 inch square) piece of inner tube between the canticle and the leather. Picture the Canticle as roughly 'C' shaped and lifting the leather up and away from the open end of the 'C' . I used pliers wrapped in cloth/tape to prevent it from damaging the leather. Releasing tension via the tensioning bolt also helps in the procedure.
Marty Eison
Frisco, Texas