Doing a radio install in an Insight is a fairly easy task for anyone who can handle a basic Phillips screwdriver. It usually takes about 10 minutes at most to remove or replace plus about 10 minutes to half an hour to do the wiring harness (depending if you've done any electrical wiring before).

Tools:
Phillips screwdriver
Wiring harness adapter (available from any electronics or car auto store)
Electrical tape or electrical crimp connectors
Wire cutter/crimper/stripper

Directions:
1. Remove everything from the glove box
2. On the passenger side, under the glove box there should be two screws, remove both
3. Now unlatch the glove box and gently turn it sideways and slide it out
4. Next, there are 3 to 4 screws on the side of the center console beneath the radio, remove all of these (note: you do not need to remove the center console where the shifter and cup holders are)
5. Make sure that all the screws are removed, now starting from one corner of the console piece (I usually start from the top right), gently pull the plastic console piece outwards (it will take a good amount of force to remove, but be careful because the plastic and metal clips on the back of it can break) if any of the clips break its not a huge deal there are lots of them and unless you break more 4 or so it will reassemble just fine.
6. Once the console is loose, remove the electrical plug connected to the back of the cigarette lighter
7. Now you should be able to see the radio unit and brackets.
8. The radio is held in place by two brackets with 4 screws anchored into the dashboard
9. Remove these 4 screws and slide the radio out
10. Unplug the wiring harness and antenna cables
11. Note where the brackets are screwed to the old radio, find the same holes on your new radio and swap the brackets onto it
12. Now wire the new radio's wiring harness/plug to the Honda style harness that you bought (usually this is simply a matter of matching wire colors and then twisting/crimping them together, most wiring harnesses come with a color guide to help you)
13. Plug the harnesses together and then into the radio, then attach the antenna cable
14. Turn on the ignition and test that everything works
15. Reassemble everything in reverse order

-When you put the center console back in place, check the metal spring clips which fit over each of the plastic pins on the back of the console, make sure they are centered and secure before snapping it back into place. Also, it can sometimes take a bit of force to reattach, use your hands or a very soft mallet to tap it into place if necessary.

-I wrote these instructions from memory so some items like the number of screws in each step my be slightly off, also, my Insight had the stock tape deck without CD changer, if you have a CD changer there will likely be an extra plug on the back of the radio to detach and reattach.