This is quite handy to know if you need to create a new network bond on a live system without disrupting traffic.
First of all create your bond configs in the normal way so that in the event of a reboot it will come back up working. See the Redhat documentation for how to do it in RHEL6.
Now because we cannot just restart the networking to bring that up we need to construct it by hand. Lets say out 2 interfaces we wish to bond are eth3 and eth4 and the bond we are going to create is bond1
Make sure the bonding driver is loaded by modprobing the module alias you set up in /etc/modprobe/bond1.conf
Create the bond interface in the /sys filesystem
echo "+bond1" > /sys/class/net/bonding_masters
Now that we have an interface we need to enslave the interfaces
ifenslave bond1 eth3 eth4
Lastly we need to start the interface up with the configuration we used in the networking-scripts. Change the ip address and netmask to suit your requirements.
ip addr add 192.168.0.100/24 brd + dev bond1