I've come across presentations on L2VPNs which suggest the below conversions are possible while using L2VPNs.
FR to ATM Interworking
Ethernet to FR/ATM Interworking
FR to PPP Interworking
All documents mention how it can be achieved using ISC 3.1. Unfortunately, there aren't any good documents which describe how the protocol conversion is done and the CLI commands to achieve them.
Any help would be appreciated.
Please refer to the following URL for some good L2VPN Interworking configuration examples:
Hope this helps,