Here is an example from one I set up recently, uses CEF per packet load sharing.
IP CEF
interface Loopback0
ip address 213.nn.nnn.138 255.255.255.252
!
!
interface Serial0/0
ip unnumbered Loopback0
ip load-sharing per-packet
!
!
interface Serial0/1
ip unnumbered Loopback0
ip load-sharing per-packet
!
ip route 0.0.0.0 0.0.0.0 Serial0/0
ip route 0.0.0.0 0.0.0.0 Serial0/1
Works a treat, gives me equal cost load sharing, only one registered IP address required, low CPU overhead.