Its pretty straight forward; the one on the left, maybe accessible without loosening of the intake but doing that would probably be easier. When, I did the one on the right (i think #2); I removed the intake bolts and pushed up the intake manifold to give me more room to work, then removed the air pump to access the sensor. This would be a good time; to replace the egr hoses; like the 034 Motorsports silicone hose kit. I used a long extension and purchased some long ball head hex bolt sockets; it is ALSO crucial, that your torque them to spec. Which might require a special torque wrench; for the low torque values given in the manual, the sensors require these specific values, to operate correctly. I used a 1/4" drive, inch pound; torque wrench (Mac Tools brand).
I decided to purchase sockets, for the job to make access easier (a new repair; is always a good excuse to buy more tools!); Harbor Freight brand, not Snapon quality but if you treat them nicely, they should be ok for this low torque situation (I didn't break mine):
7 Piece 3/8" Metric Long Ball Head Hex Socket Set
Pittsburgh - Item#67888 google search: "harbor freight coupon", for a extra 20% off.
If you already have shallow sockets with a long extension; you maybe fine using those, try them out and see if you run into any access issues. At the cheap price of the HF sockets; I found them useful for the job and also, for other areas around the engine (like coolant flanges, etc.).
I also, used your typical; Telescoping Magnetic Pickup Tool, to remove the intake bolts... after, I loosened them (available at most hardware and auto parts stores).
If you want some visual reference for the job; check out this diy, to see manifold removal: (check out page 1/2)