Control System Fan Setting - Crash Course

[Petroklos]

Hello Modders! This is my first venture to this forum and to BIOS modding as well!

The point of this thread is twofold.
A. I'd like a crash course to the whole BIOSModding experience
B. I'd like to add a "System Fan Speed" controller to my BIOS

My motherboard is a GA-H61M-D2-B3, running its stock Award BIOS.
It has control for the CPU fan (PWM and Voltage) but no control for the SystemFAN.
It displays the FAN speed of both CPU and System fans.
CPU header is a 4pin PWM, SystemFAN header is a 4pin nonPWM (according to the manual, 4th pin is "reserved")

So can I mod my BIOS to allow Voltage control for the system fan? What BIOS(mod) need I download and how would I install it? Any specific precautions and tips or tricks? Blocks of text or links to articles are welcome!

Thanks in advance.