The "E" string makes a very good tool and you may get one which has broken at the end at your local guitar repair shop.
Bend it in half and it becomes a very nice, long, flexible needle. Cut your sleeve material about 18" long and thread it onto the tool.
Now burn the ends of your sleeve material to stop fraying.
Slip about three inches of your new line through the loop in the guitar string, then pull the sleeve off the guitar string on to the line.
Carefully hold end the sleeve in one hand as you pull the line back through being sure to leave about 1/4" of the line protruding out the end of the sleeve.
Tie a simple overhand knot at the end of the sleeve securing the kite line.
Hold that knot in your finger tips and with the other hand stretch the sleeve down the kite line.
Now fold the ends of the sleeve together and tie a couple of overhand knots about half an inch apart and your line is sleeved.
Leaving the 1/4 inch of line showing out the end of the sleeve makes for easy line length adjustment later if needed.
Hope this helps.
if you put a "stopper knot" into the line BEFORE you form the loop, you'll have the pull tab you seek in glove weather. When you make unsleeved line-sets this is a requirement, othewise you'll find the raw spectra has jumped over any knot tied into the loop at the end where you attach to the pig-tail on the bridle (or handles). I highly recommend NO SLEEVING on the end that attaches to the kite though. Most of the tangles and twists of set-up are pushed out easily without all the crap dangling down or offering a spot to tangle-up or snag. -plm