The first step is negotiate with the Sunnis Muslims, who represent almost all of the insurgency. If their participation in the new government isn't enough, plan B is to divide Iraq and set up a Sunnis Muslim country. That would eliminate almost all insurgency, and move Sunnis into one location. If they want to continue the terrorism, then we have front lines and conventional warfare, the type of conflict US troops win easily.
Step two is to focus on the non homegrown insurgency, the non Iraqis flooding over the border for the sake of jihad or to be terrorists in training. Iraq is currently serving the purpose their training camps once served, and serving that purpose better. As has already been demonstrated in two border operations, this is also conventional warfare with front lines that has resulted in the foreign insurgents getting wiped out.
You have to think outside of the Bush envelope. My response doesn't fit your cut and run, as it redirects our efforts more effectively at the people that were the original targets after 9/11. Almost all of the 9/11 insurgents were Saudis, including Osama. We also now have reliable intelligence that Osama is in Iran. And Iran may be developing the real weapons of mass destruction.
You have to think outside of the Bush "envelope." This isn't the only way to conduct war against terrorism, but it is the only way in which Haliburton and other corporations will get rich and control OIL.