On what basis did you decide that the 89S8252 is suited to this task?
You must surely have considered just an outline of the design to get an idea if it's actually "do-able" with this processor?!
So, having done that, you just need to flesh it out into some more detailed software design.

If, at some point in this process, you have some specific questions - then by all means post them here; but just "GIMME CODE!" is unlikely to get you very far (as you may have noticed...)