I don't think the class 'Boy Scout' has been invented. (As a Scout leader that would the only one I can think of)
However, if the player has seen the use of the skill and noticed how innovative it can be, then have him/her look into the classes that use the skill and make it a character focus, not a class focus. For instance, the Ranger of Rogue are both skill point heavy and have Rope Use. Instead of focusing on the proto-typical Aragorn adn Thief aspects, have him think of things that might fall in that category and pattern the role play after it.
For example Rogue, Circus Performer, Escape Artist. The Rogue focuses skill in both Escape Artist and Rope Use. He is very adept at both the tying and untying of complex knots and recieves sygergy bonuses when using either skill with the other - create a Feat called Escape Artist and require him to take it to explain the synergy.
Or one with Rope Use and Craft(trap making) - this rogue (or ranger) is an expert trapper, raised in the woods (or whatever terrain) trapping fur bearing animals. Was approached to help apprehend a rather elusive criminal, upon his capture the character sensed a new direction in his life and become a trap focused bounty hunter.
Creating a class specifically for Rope Use (or any single skill for that matter) is probably doomed to fail (IMO), but using existing classes in ways that are outside of the norm as a template for something new (and the rogue and ranger are just ripe for the plucking in that regard) is probably going to reap much better rewards and role playing experiences for your player.
My 2 coppers,
Happy Gaming.