Ok, it's high time I wrote up a document on how to rig a Laser 2's traveler. I'm not going to get deeply into why it's done this way. Succinctly, people often comment this "doesn't travel." Yes, it does - it travels vertically. Why is it better than the original horizontal traveler? Because it allows you to get the boom closer to the centerline, and gives you more exact control over sheeting distance. Increased sheeting distance = increased twist.
The concept is this: the entire traveler is a huge bowline with the lower mainsheet block fixed to the center of it. This bowline forms an equilateral triangle, and when you pull the control line, you are shortening both sides of the triangle equally. Thus you are lowering the block while keeping it in the center.
Note: there is a modified technique which uses the leftover block that you sold to the laser sailor to give you 2:1 purchase on this system. I recommend against this because that is not enough purchase to overcome the friction in this system. Whether you do it or not, you will not be able to tighten the traverl by pulling on the line where it exists the cleat if there is load on the main.
To tighten this traveler, you must remove all load from the traveler line. There are two ways to do this: Ease the main itself, or better yet, hand the tiller to your crew, grabe the lower main block by hand, and pull it down to create slack in the traveler. Then with your other hand, pull the traverl line where it exits the cleat.
Easing it is very easy - but do so sparingly; keeping in mind how much trouble tightening it is.