There are BPMN shapes available for Visio 2003. They can only be accessed
via the "Search for Shapes" feature in that version. With a live Internet
connection, enter "BPMN" in the "Search for Shapes" field at the top of the
stencil window on the left and all the available BPMN shapes will be
returned. One caveat is that they are based on a pre-1.0 version of the BPMN
specification.