What vehicle is it?
There are severla articles about boxng and strapping frames over at Pirate, but if you don't spend for a red star, you can't search right now...
With a Jeep frame, save the hassle, toss the stock frame in the trash and build a new one from 2 x 4 x 0.120" steel tube. Everyone I've seen who boxed in their frame *correctly* said they'd have built a new one from scratch, as its much easier.
I'm planning on building a new frame for my CJ3a in the fall.