I bound with an abdominal medical binder from the pharmacy back in the 90s... So I haven't worn/handled the fancy stuff you guys use these days.
However from what I know about making and modifying clothing items, you're likely going to have a hard time fastening the binder if you just cut it and don't add in more material. Consider a front fastening if you do choose to modify it so you have a hope in heck of being able to bring the sides together, as you will be able to hold both sides at the same time there.
You would want to use velcro the entire length so there won't be as many stress points, and you will want to sew it very securely, at least along the edges, but down the middle of the strips too wouldn't hurt.
Good luck.
Shortman