So you need to remove the frame grounding tang and solder/put a wire on the winding.
Then put two connectors on the new wire at the regulator one goes to the AC side of the regulator.
The other to your AC low power lights using the green lead.
Do not to ground the low power AC lead coming from the new wire to the regulator.
If you need to frame ground for the low power AC side of the treats winding ground the green lead to the frame.
@ AJA wrong the ground tang is the center tap for the two windings. (edited)