In years gone by I always ran the wires to the existing toad lights and used diodes. For the past two cars I have used the separate bulbs. As someone said, my connector on the rear of the MH was wired for 4 wire. If you get a blue-ox wiring kit they even show you exactly where to drill the hole for the extra bulb. What I like about this way is that there is NO way the toad electrical system can be compromised. Anyway, the separate bulb is the only way I'd go now providing there is a place to put the bulb.
Ed Headington