Heads Up :
The post you are writing will appear in a public forum. Please ensure all content is appropriate for public consumption. Review the employee guidelines for the community here.
You could have the ASA5510 place in parallel to the Hotbrick using the dual isp feature of it. Assign 1 IP from the T1 and DSL IP pool to outside and backup interface. The client vpn will have the T1 as primary vpn and DSL as backup.