John,
I have a similar shield. Not the JC Whitney one, but similar $49 dollar job. Here is how I installed it. It ended up being very ridged.
You need a dremel tool to cut the plastic around the turnsignals and some electrical fasteners and rubber coated cable holders found at Home Depot for a few bucks. I aso used the dremel on the inside under the shield so that I could clear the spedometer and tac better. I finished off the edge with some door guard found at Pep Boys. Here are some picks that might save you a few bucks.
I don't think I spent more that $10 bucks on the hardware.
Mike