Every Honda I have ever worked on has had "options connectors" in the
fuse box. This is a collection of spade connectors useful for powering
accessories. On my '94 Civic there are 5:

2 constant power regardless of ignition
1 power when parking lights are on (including when the headlights are
on)
1 power with ignition is "ACC" or "RUN"
1 power with ignition in "RUN"

See http://www.geocities.com/ng_randolph/Civic/options.jpg for a photo
of that fuse box, options connectors circled. Your fuse box will look
different, but chances are the options connectors will look similar. Get
out your voltmeter and check which ones have power when you need it. On
my car, two of the options connectors did not have power, as the car
comes from the factory without the relevant fuses. Those fuses are used
to power the DRL circuit, so Canadians got the fuses, Americans did not.
If you run into this problem, just get a spare 10A fuse and move it
through the empty fuse holders.

Don't plug a SkyFi directly into 12v power.  It uses 6v, and that
cigarette lighter plug is the transformer.

When I did this with a SkyFi, I ran a Radio Shack cig lighter plug off
of the fuse box and mounted it down low, and plugged the SkyFi into that.

On my 2000 Accord, there was an empty fuse slot that was intended for
the user to plug anything into, from what I could tell from the
documentation.  I found a piggyback fuse system with a wire coming off
of it, designed to do exactly what you're looking to do--tap into the
fuse box--but without doing any weird surgery.

You can get 12 volts at the battery. Make sure you add an inline fuse.
Since your car is under warrentee, I would stay away from the fuse
boxes.

You can ground anywhere there is metal that is connected to the body.
Look for a black wire grounded to the body, unscrew it and add your
wire. Don't just twist on wires, use crimp-on terminals.