I want to put the toilet on a platform so that it becomes accessible to a handicapped person who has limited atanding ability

Lot easier to put on an elevated cushioned seat or a handicapped seat.

http://cdn1.bigcommerce.com/server4200/0m55v9/products/279/images/763/12013__95381.1376927232.171.171.jpg?c=2 (http://www.alliswellmedical.com/raised-toilet-seat-12013/)

Why spend all that money and tear up your house? Why not simply do what I did when I brought my mother home.
Go into a medical supply house and ask for a elevated handicap toilet seat. With what you've saved you can take Mom out for a nice dinner. Good luck, Tom

Not sure if your town or county has a place that loans medical equiptment or not. I was able to get the use of one. The are very nice and the arms or handles are easily moved out of the way, 100% better than a portable. You may want to look into the raised toilet that adds several inches to the height also.

I'd install a 24" grabrail on the wall too, at an angle (if the toilet is next to a wall). Spend a lot of time with the person who will be using it to determine what height he or she likes best, after you put on the donut to raise the seat. Many frail people can't stand completely with just the rails on the side of the toilet, because they are a bit behind you when you are standing.

There are even floor mounted guardrails for the open side. (Expensive though)

A bedside chair-commode (with a smooth sided removable bucket) is very handy too.

Hi Pygalics

How tall is this person and how/why is the standing ability "limited"?? This information is especially important as the 24" requirement you mention FAR EXCEEDS any normal ADA compliance standards...;)

Here, I cannot recommend 24" to the toilet seat for anyone, and for sure, as Joypulv mentioned, you will definitely need grab bars installed in the right places.

Please provide a little more detail, especially why you are suggesting the 24" height, OK?

Mark