I don't know about pigtails, but IIRC, the JK uses a unique energy-saving H16 bulb that draws 24 Watts. Since Chrysler tends to use too-thin wires to start with, plus you have the PWM modulation on the power circuit for computer monitoring and control, I think trying to hook-up standard 55W halogens or even 35W HID's will be a problem.
Instead, what I'd do is just tap into the hot lead someplace on the fog light wiring bus and use that to trip a relay that actually powers the fog lights. Not only will this maintain and protect the OEM wiring and keep the TPIM from taking a crap, you'll get full brightness out of your new fog lamps. Just remember to put a capacitor across the relay's trigger inputs to filter out the PWM and a diode in-line with the trigger input from the fog light bus to protect the TPIM from the reverse voltage surge that occurs when the magnet in the relay de-energizes. Search the electrical tech forum or PM me if you don't understand what I'm talking about.
I'm a JKO Reject