Congrats on the GRiSO - I have a 1100 also.
You'll find a link to Carl Allison's excellent wiring diagrams in the 'Ex Libris' section of this website, under the 'online manuals' tread.
(Blue is the ground).
However, if you're adding significant current draw (ie large lights) I would run a separate fused, feed from the battery. Otherwise, you'll increase the load on the existing wires and (more importantly) the switch contacts in the bars.
Good luck, and remember the Harley Mantra: "If you can't fix it with a hammer, it's an electrical problem".