I'm putting a 05 5.3L in my truck too. I'm going to use the fly by wire. I already got the gas pedal and TAC module. The intake, throttle body, injectors, wire harness, and ECM are in the mail and I'm picking up the longblock this weekend.
Here is a link to my thread on LS1tech that has a wiring diagram of an express van....it uses a cable actuated TB.
http://www.ls1tech.com/forums/showthread.php?t=781682