the styrofoam trick is a myth, in my opinion. it will provide a safe and stable platform between the tank and the stand, but not help with anything else.
your tank should be fine without one, if your really worried about it, you can go to a LFS
(not a chain store) and ask them to special order you a new bottom frame. i had to do this for the top frame of a 55gal yrs back, and it ran me about 20bucks and 2 weeks of waiting.
putting it on shouldn't be difficult, just make sure the glass is clean and free of any silicone from the last frame, apply silicon to the inside lip of the frame and insert your tank, after your sure its seated correctly put some weight on the top of the tank, i would think 100 lbs or so would good for this, let it sit like that for 24hrs and you should be all set.