Its possible, I did this by using an IPSec encrypted GRE tunnel,this passes EIGRP updates. EIGRP also runs across the point to point link as well.
So in the routing table I see a path via a frame PVC and one via the VPN. Adjust the bandwidth (or delay)parameters so that the VPN path has an equal cost to the poit to point and it will load share on a per session basis.
I based my configuration on information in the following URL:
http://www.cisco.com/en/US/tech/tk583/tk372/technologies_configuration_example09186a00800a43f6.shtml