Guys, I just did this on a 2010 Standard Ultra Classic, and it works fine. While I have not done this on a 2010 SEUC, which might have some minor difference due to the locks switch, the principle and logic is the same.
Essentially, the yellow wire provides 12+ to the +coil of the spot relay from the LB circuit. When the LB/HB switch is cycled to HB, it losses power and you loose the Spots. As such, all you are doing is splicing the yellow wire into the incoming side of the accessory switch that has full time 12v, while the ignition switch is in Ignition or Access.
Now, due to the locks swtich, they might have changed things around a bit, but you should be able to very easily associate these instructions to make this work. When you have the panel open, find the yellow wire. With the Ign off, use a meter on the switch terminal and see if you have power to it. S/B no. Then put the Ign to Ign and on LB's. You should see power now. If you switch to HB's, their s/b no power. Once that is confirmed, you are set on the yellow wire. Following that wire, it goes to the right side of the neck into a loom going towards the fairing.
Then go to the accessory switch. Turn the ign switch to Ign. Turn the accessory switch OFF. Check each terminal (and attached wire color) and take notes of those showing power. Then flip the accessory switch to on. Again, take note of which terminal has power. One will have power under both conditions (on and off) and one will have power only with the switch on. The wire you want to tap into is the wire that had power when the accessory switch is on and off.
The bottom line is, it doesn't matter where you get the power from, you simply have to tap that yellow wire into a full time power lead (with the ignition on) to enable the spots independantly of the HB/LB selection.