Need help configuring balance 30 for 4G failover

we have dedicated 20Mbps fiber circuits connecting all branch offices to our central office in an any-to-any virtual LAN topology, with Cisco 2821 routers at each branch edge and a cisco 3845 at the main office hub.

I purchased a Balance 30 configured for Sprint 4G to install at a branch office as a failover, but am having problems getting the vendor who sold me the peplink to help me work out how the actual failover can be configured. They showed me how to configure the peplink 30 itself, but I am unsure how to handle all the Cisco configuration changes necessary to properly route traffic over the peplink tunnel in the event of a failover, and the VAR seems unsure about how to do it either.

I found one forum article describing using two balance routers, one at each end of the dedicated circuit and in front of the Cisco edge routers, is that the recommended method for making this work?

Yes I use that sort of setup. What do you need help with?