Mark,
Yes you can.
For phones and Hunt groups, it's done in the COS. It's the Call Forward No Answer Timer.
For Agents, it's also done in the COS of the phone IF the agent is called directly. Otherwise it's done in the Path assignment form.
Some of this is depends on your exact configuration. If you are using the call re-routing second alt. then the call rerouting timer in the system options takes over.
Ralph