Okay. This is a hard one. I did a pattern once that required it, and my advice is to accept the fact that you are either going to rip out occasionally, or have a few imperfect spots.
What you are going to do is look at the pattern. It repeats, right? So your first increase will be at 6 1/2 inches. You put the extra stitches inside your selvage, and on the next row, when you have to deal with the new stitches, look at your chart, and see what stitch comes right before the first repeat. In other words what is the last stitch of the repeat, that should be the stitch you use on your new stitch, then start the pattern repeat as usual. When you increase again, the next row after is where you have to deal with the new stitch. You look at the second the last stitch in the repeat, use that stitch for the new stitch, the last stitch of the repeat for the next stitch, then start pattern again from beginning.
Does that make sense? When I did it, I actually mapped it all out ahead of time and made myself a new chart, including the new stitches, so I could visualize it.