Check out the sub-development branch of this library for additional functionality and support for MCP2515 controllers with 8MHz crystals.
MCP_CAN Library for Arduino
MCP_CAN library v1.1 This library is compatible with any shield or CAN interface that uses the MCP2515 or MCP25625 CAN protocol controller. Baudrates 5k, 10k, 20k, 50k, 100k, 125k, 250k, 500k, & 1000k are confirmed to work using a Peak-System PCAN-USB dongle as a reference.
Installation
Copy this into your "[...]/MySketches/libraries/" folder and restart the Arduino editor.
NOTE: If you have an older version of the library (CAN_BUS_Shield) be sure to remove it from the libraries folder or replace the files with those in this library to avoid conflicts.
Happy Coding!