I think he's suggesting to buy an invertor that uses a cig plug, plug it into that adapter, and then hardwire the adapter.
Maybe he's not aware that there are plenty of invertors readily available that have posts where you just hardwire them directly (like an amp). That's the only way to go, imo, unless it's just for a one time use or something.
I got a real nice one at Fry's a few years ago that was around 1,000 watts and had 3 outlets, but it was stolen when they jacked all my stuff in 2006. I replaced it with a cheaper Black and Decker model that is 750 watts and has two outlets. I think I paid around $50 for it. I ran 8ga power and ground and a 40 amp inline fuse. Works perfectly.