The front 3 wires (1-3-5) go into a plastic bracket clipped to the front end of the front valve cover, and come out where the green arrows point. Note: wire 1 should loop BEHIND the dipstick tube and wire 5 BEHIND the lifting eye bracket, or else they can be slack enough to get chopped by the fans.
The rear three wires (2-4-6) loop over the UIM, and are held in place by three "snap" brackets indicated by the red arrows, one on the EVAP bracket, one on the fuel rail, and one on the rear bracket that holds on the cover.
EDIT: I see other pix were posted while I was doing my response...
2004 Buick Lesabre Limited, Gran Touring; Bone Stock
1998 Buick Lesabre Limited, Gran Touring; Mods: Poly sway bushings/endlinks, Tru-Cool trans cooler, Thrasher shift kit (med), PLIM, front PEM; Mods in progress: Alot of stuff, but slowly...