The most common piece of hardware to do this is by using a flat keeper plate.
Once your tensioning is complete, all your clamping and deadend hardware is tightened and adjusted to hold your messenger strand in place. Here's a couple of examples of your flat keeper plate at your pole.
Hopefully I've given you some good information to help you with your installation after you've purchased your figure 8 cable and hardware from Discount-Low-Voltage.com .
"By Mercy Salinas"