I accessed the injector power lead at a large connector (my Civic is '97, Gen 6) near drivers side hood hinge. Aside from having to snake a wire through an existing rubber boot in the firewall, the job was not too difficult. I definitely don't relish the thought of working through stuff behind the glove box.
Here's the post.
http://ecomodder.com/forum/showthrea...tml#post175914
Go to the first post in thread to see photo of the connector.
The link above tells which wire it is - it's not the fat one easily visible in photo.
If you're not handy with relays like I am, there's nothing wrong with using a simple switch on the dash, as long as you have good solid connections at every point along the way. Probably should use a wire just a bit thicker than what you cut into, because you're adding length to the run. My switch is a toggle and I like it. Flip it off to kill, flip it on again right after engine dies to re-enable fuel injection. That way when you bump it to start, it will catch. If you use a momentary disconnect instead, then you need to hold it down till the engine dies. That's less convenient, imho.