Typically you are going to call an ACL to match the traffic source and type.
ip access-list standard PBR
match address PBR
set next hop x.x.x.x
Beyond that, there add'l options like verify reachability calling an IP SLA. What is the end result you are looking for?
Rob Riker, CCIE #50693, CCNP Service Provider, VCP5-DCV