Below is an explaination of the system that I rig on my Mako and Charlton fly reels, which I use for billfishing and use to teach with in my schools. This system is now very popular and is used widely by many top-knotch crews who fish seriously for billfish with fly tackle in Australia, Panama, Costa Rica, Guatemala, and in the Caribbean. There are other systems that will work, however this one is designed for fishing for blue marlin and black marlin which means that when using it for striped marlin, white marlin and sailfish, I never have had it fail. The text below was copied from my website. Feel free to e-mail me for more detailed information.
First I tie the 50 or 65 pound GSP, backing to the reel with a 3 times around the arbor improved clinch knot, then I wind on the correct amount of backing to the reel which I am loading, and then I cut the backing. Next I tie a 40 turn Bimini Twist in the end of the backing, and then double it to use as a loop to loop connection.
The next piece to go on the reel is an 80 foot long piece of 50 pound test Suffix Elite florescent color monofilament line, this is referred to as a "running line" and is used as a shock absorber. Each end of the running line gets an 80 pound test Dacron loop (about 15 inches in length) installed by sliding the running line up into the doubled Dacron loop and then it is stretched using the Chinese finger torture method of grabbing hold of the enclosed monofilament, and then each loop is served in place using waxed rigging floss. (This technique is similar to how wind on leaders are made for use in big game fishing). Now you connect the finished running line to the backing using a loop to loop connection.
The next part is the 30 foot 550 grain RIO Leviathan fly line with heavy core (which I worked with RIO to develop, many years ago). You then install the same 80 pound dacron loops on each end which you used on the running line, and then connect the running line to the fly line using the same loop to loop system.
The last piece to be installed is the butt section of the leader, I use 80 pound test mono with a doubled dacron loop on one end and a crimped loop on the other. Connect the fly line to the Butt section of the leader by using loop to loop with the dacron loops. Wind this on and you are finished.
When you string up your rod you then connect the 20 pound (or lighter) class tippet from your fly to the butt section of the leader looping the doubled end of the class tippet Bimini to the crimped end of the butt section of the leader. The Bimini on other end of the class tippet is connected to the 100 pound bite tippet using a huffnagel knot, and then 11 inches away the bite tippet is connected to the fly. You are now ready to catch a marlin, sailfish or tuna, nothing will ever fail except the class tippet if you make a mistake.
I hope that this explanation is clear enough to understand. Each part can be replaced by un-looping from the other sections. Using this system, the only part that should ever fail would be the 20 pound class tippet unless you do something wrong to cut a section of your total system of lines. Feel free to contact me should you need more information or don't get any of these parts.