But let's begin..shall we?
Here I have my sample seam. I chose a three thread overlock which finishes the edges nicely and still allows for a lot of stretch. My seam allowance is 3/8" and my overlock takes up a scant 1/4". After sewing a few samples and stretching them I determined I would need to use the stretch stitch on my Bernina. If your machine does not have a stretch stitch just set it to do a very narrow tight zig-zag and then pray again for patience, because this stitch moves slowly and you cannot rush it. Settle in, get a nice cup of tea, put a movie in, whatever it takes, but you have been duly warned.
I only use this stretch stitch for extreme active wear situations. You will not want to use this stitch on a rayon jersey for instance, as it's overkill for soft delicate knits, but it's quite necessary for something you want to do lots of stretching and bending in and you want the fabric to stay with you.
Additionally if you do not have an overlock you can just trim back your seams and use a normal zig zag to finish them together.
Start with basting you inseam and then baste your side seams, so you can check the fit before preceding, unless you are using a tried and true pattern. After the fitting you can sew your seams again using your stretch stitch and overlock.
With the inseam and side seams sewn its time to sew the waistband on.
I then create a loop out of my elastic by overlapping the opposing short end to match the chalk line and sew a box.
From the right side and using a zipper foot, stitch in the ditch of your waistband, catching the inside seam allowance as you go. This will create a nice flat attachment.
My pants are sewn...that didn't seem so bad. They just need their hem.