I used to do a lot of Taekwondo and hence would say have more muscular/thicker leg muscles than average. I'm flexible enough to get into the shoelace, but what's preventing me from getting there in the end is my leg muscles pressuring my testicles too much - as weird as it sounds.
Is there any way I can get around that?
I have tried positioning them above and below the legs, but it wasn't good really...
If the boys are complaining - move them out of the way! If moving them out of the way doesn't work, move out of the pose. Not all postures work for every body, which is why we have so many poses! Remember what your intention is for doing Shoelace. Was it to open the hips? [ie - stress the hip sockets] If so (and that is normally the reason), try another hip opener - like Square Pose, or Winged Dragon, or Swan. Those poses should present no problem for the boys.