Firmware Upgrade of Apple Mac Pro (Early 2009) from 4.1 to 5.1 Apple Mac Pro (Early 2009) running El Capitan OS 10.11.6
Connecting to the internet via a D-Link DWA-131 WiFi USB Dongle

Hello, I am trying to carry out the infamous 4.1 to 5.1 firmware upgrade so that I can upgrade my existing 10.11.6 OS up to Sierra 10.12. I have established that I need to carry out the following steps:


Boot into recovery mode and disable SIP since I'm running El Capitan
Reboot
Mount the MacProEFIUpdate dmg (for 5.1)
Run MacEFIRom's utility.
Shutdown and power back up by holding the power button until light flashes and beep sounds
Verify Boot ROM Version: MP51.007F.B03
Boot into recovery mode and enable SIP
Reboot
Reset PRAM


The problem comes at step 4. As far as I can see, the act of disabling SIP, also disables my internet connection. This causes a road block because the MacEFIRom utility will only run if the internet is active. So I cannot run step 4 and beyond. I might investigate the possibility of running and Ethernet Cable to the front room where my WiFi Router is, thus bypassing the wireless aspect of the connection. Other than that I'm out of ideas. 

Can any anyone tell me how I can achieve all 9 items on the list? Or indeed, if my list of steps is incorrect please can you correct me?
I ran an ethernet cable and was able to progress through the list of tasks. It took two attempts to pass step 5. The trick was to keep the power button pressed well past the flashing of the power light and only releasing it again after the continuous tone has sounded. Long story short, I now have the 5.1 firmware installed, and have upgraded to Sierra 10.12.5.