Modding a Vaio E BIOS - precautions

[Gerinych]

Little preface:
Recently I replaced my internal Wi-Fi card, but it doesn't seem to be working with my laptop. While it is being recognized by the system, it doesn't pick up any wireless networks. I've checked it in Linux using rfkill, and it said that the Wi-Fi card is hard-blocked, and nothing I tried to fix this have worked. The card is an Atheros 9280, which I pulled off an old netbook. Since it worked fine while it was in the netbook, I thought that it was possible it wasn't whitelisted by my BIOS.

I've looked around the forum, but I haven't found any confirmed mods for my BIOS, so I've decided to take the matter into my own hands. I looked up the VID and PID of my old card in the rom file in a hex editor and found only one match for it. My plan of action is to replace that particular 4 byte segment with the VID and PID of the Atheros card. However, I want to take some precautions in order to avoid completely bricking my laptop.

Is my plan going to work? I've heard that some BIOS roms are DSA protected in order to protect the system against anything malicious or well-meaning modders or whatever. So, in case it's protected, will the flashing fail or will it actually flash it, bricking it in the process? Finally, in case worst comes to worst, what is the procedure for reflashing the BIOS with a stock rom?

This is the stock rom I'm talking about, just in case:
http://www.sony-mea.com/support/download/554056

Edit: the stock rom is in a CAP file.