yeah
get your kecks good and comfy, put your knee pads on, mark where the lower strap crosses the outer seam while you're standing, then crouch down and check that the elastic will stretch far enough to stay comfy - make the loops a bit wider than you need for ease of use
I made my loops out of bits of DPM I cut off the lower legs of another pair I made into shorts, with some folded bias binding behind as reinforcement, but webbing, elastic, any cloth would do.