The fact that you have an all green picture says that your cable is correct. The problem you are having, and as you have guessed right, is the vga bios are not enabled. So you need to start your search from there, and stop worrying about the cable, because it is correct. Also, there is no need to mess with the pin setting on the AV cable if you have a MS HD pack and your BNC cable. Just plug everything together.
First, i would make sure your iND- bios 5001 vga are correct. Try the bios when on a regular connection (with composte/component/or s-video cables on a regular TV). The pictures colors should not be correct; it should be all a deep puke green (a different color of green then what you are seeing on with your vga cable on your monitor). If this is the case then the vga bios are enabled.
Now assuming that the vga bios are indeed working, and it is still not working with your vga cable on your monitor, then there must be something wrong with the compatibility with your xbox version. But you said it was a ver 1.1, and should work. Just make sure it is a ver 1.1.
Also, what kind of chip/softmod are you using?