Don't know anything about the US but here in Canada if you end up working for anybody who does work in the bush they will usually set you up with a line and a machine and let you go play for a bit. Obviously most companies that I have been affiliated with have done it this way.
Usually a job will come up and a guy will take you out and explain L/L care, maint. and use of...then go out with you and show you a few things with different L/L lengths, water bucketing, strap inspection, electrical inspections and whatnot NOT TO MENTION EMERGENCIES. Most of us up here have been exposed to it in one way or the other. As for raw talent and progression...well bud that is all up to you.
The times being what they are alot more companies are making it part of their Annual training and documenting it as well. Unlike in US though there is no real L/L course. If you show up on a job your abilities will, one way or the other speak louder than anything that comes out of your mouth and is worth more to the customer than any piece of paper.
The above does not involve CLASS D LOADS ie Humans on the end of the line. Much different story there.
BWB.