Here you go....A nice Diagram on HOW TO ADD RELAYS TO YOUR HEADLIGHT CIRCUIT.
It's actually a pretty basic install. The best place to mount the relays is next to the Horn relay area (LF fenderwell). I recommend replacing the power-wire from the battery to the horn relay with at least a 10 ga. wire. (If it's not already)
You can now run your fuse/breaker off of the power terminal of the Horn relay.
You can then unplug the headlight harness at the radiator support, and connect those wires to the relays, according to the diagram. You can use blade terminals to insert into stock harness, that way you won't need to cut your harness. (unless you want to).
The LO and HI relay output terminals (87) will now plug into the stock plug in the rad support.
You now have FULL BATTERY LOAD to your headlights...and as Bryan mention, have a cooler harness under the dash !!!!
Hope this Helps !!!
John