Hello Vicky,
for a scenario like this I recommend to use a point-to-point GRE tunnel that will be protected by IPsec, this allows you to have a logical link, the GRE tunnel, over which you can run a routing protocol, multicast traffic and even MPLS if needed.
To make it the secondary path it will be enough to increase metric over it.
Depending on what routing protocol you use on primary link different choices are possible for the protocol to be used over the GRE tunnel
if you use eBGP on primary path any IGP can be used on secondary path with only care to avoid to have more specific routes over it.
A possible choice can be EIGRP that allows to summarize out an interface or OSPF
see
http://www.cisco.com/en/US/tech/tk583/tk372/technologies_configuration_example09186a008009438e.shtml
Hope to help
Giuseppe