David
This is how I make up my insulated flying lines:

1.  I first strip the insulation off of about 3 inches of the flying line.  Either by mechanical means being careful not to damage the wire strands, or burn it off with a match.  Lightly sand the bare wire with very fine sandpaper only to remove any residue not to reduce the size of the wire.

2.  Place a 1/2 inch long piece of 1/8 inch diameter shrink sleeving over the flying line and slide it back out of your way.

3.  Using a bright silver color ferrule, available from various sources, make up the end around an eyelet as you would normally do it.  

4.  Strip about 1/2 inch of the insulation from a piece of soft flexable stranded wire two or three inches longer than you think you will need.  Using a hot soldering iron and 60/40 solder with rosin core, tin the bare stranded wire end.

5.  With the wire Laying along side the flying line solder the tinned end to the ferrule.  That is why it must be a bright silver looking one so that it will accept solder easily.

6.  After the solder cools fold the wire back so that it is pointing away from your flying line and cover the ferrule and wire with the piece of shrink sleeving you placed on the flying line in step 2.  Shrink the sleeving.  This will give mechanical support to the connection between your flying line and the electronics connection.  

Note: If you color code your lines then you will know which line is the UP and which is the DOWN line.  You can use different color hookup wire or use different colored shrink sleeving to do this.

I prefer to use a type of connector that cannot be plugged in backwards to prevent problems caused by reversing the "Signal " and Return" leads.  My personal preference is to use 3/32 Miniature Earphone plugs on the lines and jacks on the handle and model.

The attached picture is of the under side of the wing tip of my P-38 in 1983, Model Aviation March 1986 page 76.  You may notice that I have the insulated wire soldered on backwards from these instructions.  I hope we all have learned something new since 1983.  LOL

The use of the Earphone jack on the model leaves very little showing on the model and I always try to position it on the under side of the wing tip where it will be out of sight during most of the static judging.

I have also attached a part of the Model Aviation page that shows my C-7a and Australia Graves' KI 61.  Note how uncluttered the two models are in flight.  The radome on the nose of the Caribou contains 16 ounces of lead to balance the model.

Clancy

I didnt even think about hooking it up like that.  So the bell crank doesnt need to be insulated?  I was also trying to figure out how to make a slider to keep the two leadouts from touching.  Most of my sliders use a piece of brass that the lines go through.  The picture doesnt show the piece that slides but there is a piece of brass tubing that goes over the carbon rod and a piece of flat brass is soldered on that hangs down below the carbon rod.  The flat brass just has some holes for the leadouts.  I wasnt sure how to insulate that with something that wouldnt wear through and end up shorting out.

Thanks John

I am too familiar with doing this so I some times leave out important information.

Yes, the bellcrank and the handle both must not short the flying lines together.

As for the bellcrank if you are modifying an existing model to add electronic control and replacing the bellcrank would be a major undertaking, you can place an "Egg Insulator" in one leadout inside the wing, see picture attached and dimensioned drawing.  I left two dimensions off the drawing.  The holes are located 1/8 inch in from each end.

The picture of my Ringmaster Trainer with external leadouts has a Fiberglass bellcrank and the insulated flying lines have eyelets captive on the lines.  Each line is slipped through a thin slot in the wing tip guide to a hole and the eyelet is pressed into the hole securing the leadout function.  The actual leadouts are only about 4 inches long.  

Clancy