Hi Mikey! I have 2 setups. 1 is for handles with 'tails' coming out the back opposite where the flying lines attach, and the other is for handles with no 'tails'.
There are some pics at
http://albums.photopoint.com/j/AlbumList?u=19203 in the 'kites and buggies' bit.
I use a 'clove hitch' to attach my 'link line' in both setups. I start by tying a stopper knot in the end of the line, then clove hitch that end to the handle. Clove hitch to the other handle with about 8 inches of line in the middle and go try flying. Adjust the line length until it is comfortable, then cut off any excess and tie a stopper knot in the cut end. If the handle has tails, I clove hitch around them, which needs less line, so I use a shorter link line.
Just a thought; I use a pulley and release cord in my setup, but if you are not using this, you will need a longer link line. Try starting with a piece of line twice the length of your forearm, and work from there.
As I use a pulley block, there is no friction, but you may ned to put some form of protection onto your line to prevent it wearing on the capstan or hook. Plastic tube works well, and if it is clear, you can see when/if your line is getting damaged. If you have no joy finding plastic tube anywhere else, try looking in an aquarium supplies shop.
If you would like more pics, let me know and I can go and do them...all the gear lives in the car!
Hope this helps.
Best regards Andy Jersey Channel Islands.