Spice it into almost any circuit that is turned on with the ignition accessory power. I think there are a couple extra around the radio ( don't use the radio as it might cause noise ) but any of the lights like the ash try light, glove box light etc will supply enough juice to flip the relay and turn on the big juice.

I'm not a big fan of splice crimps, most of the time I pull the connector apart and solder in a new wire.

98 Montero with cold weather package
96 Toyota Land Cruiser, fully locked Mall Machine :-)