Building a CAN API for Arduino DUE

Hi guys,

at the moment I'm testing several CAN examples (Adder + modified ASF example which is very similar). Does it work by simply crossing the lines?
CAN0 TX <-> CAN1 RX
CAN0 RX <-> CAN1 TX
Unfortunately I don't have a transceiver here.

I'm trying to listen to the data stream with a led (have no scope available at the moment), but even with lower speeds it seems the modules are still disabled. Wonder what's going on here.