Hey, literally just swapped mine yesterday, (4.6L too). It's where belvin mentioned. If you look under the side of the car, you'll see that little diamond indicating the front passenger side jack point. It's almost on the other side of that after your fuel tank, (big honking black thing almost directly under the passenger seat).
I pulled my fuel relay fuse, (#49 in the hood box i think), tried starting the car a time or two to depressurize the system, jacked the car up a bit and slid underneath. It's a beeotch! You need 3 x 13mm to remove the heat shield, (one of them is a pain and you might need a wrench if you don't have the right socket adapters), and then 2 more 10mm bolts. The screws the 10mm attach to make it so that you need a deep wall socket - or again, go with a wrench. Once you remove that bracket, (weird angle to get it out), the filter will be right there. The inlet side has a red clip that you first have to "unlock" with a flat head screwdriver. Then squeeze and push up. The outlet side, (green clip), can just be squeezed and pushed up.
It's really hard to explain the clips if you've never done it before, but for me, unlocking the red one wasn't so obvious. Two tips: Besides a 10mm socket, 13mm socket, and the new filter, be sure you have at least two towels, (one for the immediate runoff and the other to lay the filter on), and some sort of safety goggles. And secondly, take your smartphone! I couldn't figure out the inlet clip and was getting frustrated. Took my phone and snapped a quick pic. 5 minute break to stare at it and it clicked - no pun intended!
Good Luck!
Edit: this thread is super old....?
