Configuring routers running Cisco IOS for bridging is pretty simple. Lets say you are trying to bridge e0 and e1, the configuration would be
bridge 1 protocol ieee
interface Ethernet0
no ip address
bridge-group 1
interface Ethernet1
no ip address
bridge-group 1
It gets a little dirtier if you are trying IRB or CRB.
Lets say you want to configure IRB. To bridge over e0 and e1 while routing over s0 and s1, the config would be
bridge irb
bridge 1 protocol ieee
interface Ethernet0
no ip address
bridge-group 1
interface Ethernet1
no ip address
bridge-group 1
interface Serial0
ip address 10.10.11.1 255.255.255.0
clockrate 64000
interface Serial1
ip address 10.10.12.1 255.255.255.0
clockrate 64000
interface BVI1
ip address 10.10.10.4 255.255.255.0
You can find additional information at http://www.cisco.com/en/US/products/hw/switches/ps5304/products_configuration_guide_chapter09186a00800f0a16.html