Rather than spend a bunch of money on exotic tape, I have been using the same stuff you can buy for $3/roll at the drug store in the Band-Aid department. It's just a white cloth tape, about an inch and a half wide. I tape up my tiller extension just like I used to tape the top of my hockey sticks, by first pulling out about two feet of the cloth tape, stick the loose end to the tiller extension, spin the roll of tape so the 2' extended tape will wrap up into a tight cord, then wrap that cord around the tiller in a descending spiral, and then wrap the wide tape over the top of the cord. Here's a picture which is worth a thousand words!

Well... the picture won't post, so to get a good look go to 'googleimages.com' and put in 'hockey stick grip tape styles' and you'll see what I'm talking about. There are a couple pictures of guys taping up their sticks, you can see the cord underlying the tape, which makes for ridges on the finished product, which makes it much easier to grip. Instead of doing the entire 6 feet of tiller extension, I put about 18" of grip wrap in the two locations I use most often, 1. At the very end of the stick for when I'm out on the wire, and 2. About the middle, where I would be holding the stick when I'm not on the wire.

I found a YouTube video of the procedure: https://www.youtube.com/watch?v=JDmkSfMfEzc