I am not exactly sure what you are attempting to accomplish. The main goal of bonding is failover in the event that one of your network links fails. If all 3 nic are bonded, and connected to DSL... your bottleneck (speed limitation) will be that of the DSL link. You're not going to increase your DSL speed by bonding multiple NIC to the DSL connection.
Additionally, all links need to be a part of the same VLAN.