Cheat Engine

[neowrs]

___asm
{
mov [ebp-0000004C],eax
}
how can write something using C# to eax such as mov [ebp-0000004C],001E9874 <<< something like that

[Zanzer]

Use WriteProcessMemory to write the bytes which make up that instruction.
Since your new instruction takes up more space than the original, you'll need to find something else to get rid of.
If you're lucky, you'll no longer require EAX anywhere.
So if the previous instruction sets EAX, you can overwrite it as well.
Otherwise, you'll need to allocate new memory and write the corresponding bytes responsible for jumping (like CE does).
Use the search at the top of the forums for writing code caves and jump routines.

[neowrs]