I just installed tow hooks (the factory ones) last week on my 06. I did it with a little help from my wife in about an hour. I was able to get them in without removing the bumper. The set I did on my 03 I did take off the bumper. I would advise not removing the bumper. If you do one side at a time and mark the alignment of the brackets before you take them off, it is a breeze. The bumper will move very little and is easily put back in proper alignment with one hand while you tighten one bolt to keep it in place, then tighten the rest on that side and then move to the other side. I removed the two small bolts holding the intercooler and by lifting it about an inch, you should be able to move it forward enough to slip the brackets in place and install the bolts. My wife just held the wrench so I could tighten a couple of the bolts from the back side. My kit came with all necesssary hardware.
I agree with Pawpaw about the Grade 8 hardware if yours didn't come with any.