Not really so straightforward. To "transform" 'push eax' into valid bytecode you need a compiler bundled with your program, plus operation are variable-sized. Besides this you can compile it by hand and get its bytecode and "copypaste" it to that address with no efforts.
Ok, I did a little test.
Get your nasm copy ready.
Create your code you want to add into a test file.
Run nasm-shell from the Programs menu.
nasm (file) -f bin -o (output)
It's either nasm or nasmw depending on which version you take.
The output file contains the raw machine code you need.