The "U" thing won't work if you are wiring more than 2 pins. I HIGHLY reccomend wiring all four (4-3-2-1). If you are going to go to the trouble of doing this, you may as well release all voltages. You should have 1.5 to 2.2 available when you are done. If you only do wire the 4 and 3 pins, this will only give you a max of 1.85 volts (1.7 default) and if your mobo is like mine, the actual MBM voltage will be 0.05 to 0.075 less than the BIOS setting.
Do it once and do it right. I ended up doing the 3-4 and then went back and wired them all.