Hadji,
You don't really need to simulate a load cell, and you don't have to have a drawing to install one. Instead, use the real thing. You can buy small inexpensive low-weight load cells. Buy a load cell, mount it on a support, hang a box, hopper, or bin of some type from the load cell. Connect the load cell to a DC voltage supply (that matches the requirement of your particular cell) and a weight transducer or weight controller, and you are in business with a real load cell, not a simulated one. Put a weight in your load box, and read the weight in whatever units you have calibrated (usually grams, kilograms, or pounds).
Here is an Omega type LCL load cell that measures up to 40 lbs for $75.
http://www.omega.com/ppt/pptsc.asp?ref=LCL
The Omega DP25B-S provides excitation voltage and reads a load cell input, for $250. The older cheaper DP25-S is still available as a special order.
http://www.omega.com/ppt/pptsc.asp?ref=dp25b&nav=
Omega also sells the bare unmounted strain gages - 5 for about $35. You can purchase one of those and glue it to a metal plate to build your own load cell, but you would have to figure out how to make it work.
You might want to get a free copy of the Omega Engineering Pressure, Strain, and Force Handbook, with lots of useful information.
http://www.omega.com/literature/pressure9/