WARNING: This page is about a different car, the 2007 GMC Yukon XL and 2007 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Locating Transmission Oil Pump Cover Bolts
Courtesy of GENERAL MOTORS CORP.
Remove the transmission oil pump cover bolts (220).
Remove the vent passage splash shield (239).
Separate the oil pump body assembly (203) and the oil pump cover (206).