This is what you are going to need two relays, two 50ohm 10 watt resistors.
Put the resisor across the factory wires. Then connect terminals 85 and 86 on the relay to the two wires that you connected the resistor to. Then connect terminal 30 on the relay to a constant 12 volt positive. Connect terminal 87 on the relay to the positive input in your hid kit. Then ground the hid kit. Do this for both sides. Then you should no more flickering.
Here is what the resistors and the relays look like.
Attached Thumbnails
