NO
Let me clarify this....
The BFM is a modified BIOS, even if it's retail. The hash won't match, right? If Live detects the BIOS loaded in RAM, it will likely fail the hash check.
If the BIOS on the mod is retail, but the BIOS in RAM is not, as in the case of exploiters, Live obviously detects this... Exploiters get banned from Live all the time. So obviously, this doesn't work. This is similar to the "stealth" mode attempts in the past, actually, switching out the mod.
If the BIOS on the mod is hacked, but the BIOS in memory is "retail" - it's a BFM BIOS, and as I said earlier, the hash is different.
I don't know all of the mechanics of the Live check, but simple observation and logic have demonstrated that M$ is detecting anything but an unhacked, non-BFM BIOS for Live, and any active modchip attached to the system.