loadbalancing over 4 adsl conections with oer using dmvpn

hi i am using a cisco 2811 router and i have 4 adsl connections i am currently only using 1 adsl connection per site and i have 5 sites which i have configured DMVPN on. i now require to utilize the other 3 adsl connections at each of the site to provide more bandwidth and resiliance to the network. i was looking to use OER but i am struggling with the config can any one help!!!!