1. That didn't answer his question, at all.
2. Even if it did, they have bibs, which have suspenders.
There are lots of videos online. Just flip them inside out and lay them down flat. Next, on the inseam ( the one that starts on your inside ankle and runs up to the crotch), draw a line with tailors chalk indicating how much material you want to remove, and pin along that line. Flip them right side out again and try them on; adjust the pins for the desired fit. Once you've got that dialed, when they're inside out, sew along the line of pins that you ended up with. Then, remove the excess material.
i hope that made sense.
There are three shitty things about sewing in pants though. It compromises the waterproofing along that seam, it compromises durability along that seam, and it removes the leg vents (unless you're really crafty).
You may want to consider just selling them on here, and spring for a different pair. If not though, do some research, good luck, and post the results!
Ps, you're friendly neighborhood tailor/seamstress could probably do it a little better than you, thats another option.