Pretty sure it's under the engine cover, in a cannister. You have to remove the engine lid with your hands, and you'll see the cannister on the side of the engine, hanging off it. Remove the plastic plug on the top with a large socket wrench (I think it's about 1 & 1/4 "?) and pull on the plug and the cartridge will come out with it.
The oil drain plug underneath is I think 15 mm.
Here's something from Chevy you should read:
Bulletin No.: 07-06-01-016A
Date: September 17, 2007
Information on Internal Engine Noise or Damage After Oil Filter Replacement
2008 and Prior Passenger Cars and Trucks (Including Saturn and Saab)
2008 and Prior HUMMER H2, H3
This bulletin is being updated to include additional information on incorrect or improperly installed engine oil filters.
Please discard Corporate Bulletin Number 07-06-01-016 (Section 06 - Engine/Propulsion System).
Engine damage that is the result of an incorrect or improperly
installed engine oil filter is not a warrantable claim. The best way to
avoid oil filter quality concerns is to purchase ACDelco(R) oil filters
directly from GMSPO.
Oil filter misapplication may cause abnormal engine noise or
internal damage. Always utilize the most recent parts information to
ensure the correct part number filter is installed when replacing oil
filters. Do not rely on physical dimensions alone. Counterfeit copies
of name brand parts have been discovered in some aftermarket parts
systems. Always ensure the parts you install are from a trusted source.
Improper oil filter installation may result in catastrophic engine
Refer to the appropriate Service Information (SI) installation
instructions when replacing any oil filter and pay particular attention
to procedures for proper cartridge filter element alignment. If the
diagnostics in SI (Engine Mechanical) lead to the oil filter as the
cause of the internal engine noise or damage, dealers should submit a
field product report. Refer to Corporate Bulletin Number 02-00-89-002F
(Information for Dealers on How to Submit a Field Product Report).