Currently most people are following the tutorials on the web site to create a multibios tsop by grounding points A18 & A19. But using this method you cant use the newest multiversion bios and I was unable to get it to work at all with a V1.1 box.
A much better way is to make a switch that switches from A19-->ground & A19-->vcc. This forces the box to only read from half the tsop at a time without comparing different parts of the tsop. The easiest way I have found to connect A19 to vcc is to use this point on the lpc:
(pic is from the back of the mobo)
I would suggest flashing the bios for the first time without the switch installed first because once installed (like I said before) the xbox can only read or write to half at a time. Ground will be top half, VCC will be bottom half. But after the switch is fully working you can flash half of the bios at a time with evox. Just boot up the box and have a 512k size bios in c:bios and you can then flash half of your tsop at a time.
I have tried this on both a v1.0 and a v1.1 and both have worked fine just make sure you use the correct original bios for each. I also see no reason why this wouldnt work with a switch on both A18 and A19. Then you could switch to 4 different bios banks and could flash to each bank at a time.
Anyways I hope more people were interested in something like this besides myself.