Joined: 27-August 08
Member No.: 388964
Xbox Version: v1.4
360 version: v4.0 (jasper)
You edit the source with a text editor (like notepad, or notepad++), then compile with nasm and sign with xbedump.
If you get hold of NKPatcher11_U04.rar you can use that later version and potentially take advantage of the newer features (like runtime options), or simply take a look at the batch files used to compile and sign so you can see how to do it for NKPatcher 10.