I think it's a fairly easy install, but you need to know up front what other add ons you may do. Ex: rear speakers, intercom, XM, CB or blue tooth module (if you can find one). I added everything but the XM, use Zumo for that. I pulled that extra harness out of my bike when the old radio came out. Needed The tank off anyway to run the mass of wiring back to everything added. Ended up using the extra radio fuse in that fuse block for a feed on the oil temp gage circuit, another story....

If you are just going with the 2 front speakers, it should be plug and play, just follow what Twolanerider said.
Be very careful to check the two fairing braces where the radio attaches, these are known to crack and allow a lot of fairing vibration. It appears the radio case is used as a tie between the two braces and if it gets enough flexing, the amp for the speakers will quit (radio appears dead, cost to fix $200) due to the heat sink mounted to the case and that is where the bolts attach holding it in place. I added a brace below the radio using the 2 holes already in the braces. It took out almost all of the fairing vibration it had and improved the driveability of the bike. HD supposedly redesigned the braces in 08.5 to help, I have not had a chance to compare the older braces to the newer version.