for the intiial bend try this -- you want an anchor at base holding steady while affixed to opposite side of where the plant is bent, then typical tied down up top.
try working (Gently! don't feel any smush or excess damage to vascular tissue) the bend in multiple spots -- bend in 3 spots close to gother to make a nice horizontal plant after that point.
The anchor will keep it from bending through the soil... it's easier to make a 90 degree bend if you work a few spots together to form the bend. heck, use a third tie in middle if necessary... the plant will continue to reach upward with any growth tip... keep it as level as possible and growth will be even... simply tie-down anything taller for a day or 2 if needed.
if the plant is tugging too hard, than 3rd tie down will help hold it steady. i think if you work the bend a bit, it won't be pulling with as much force either.