Buy the cable? It's just a female RJ25 connected to a female DB9. Is the digikey part specially shielded? I don't have shielding over any of my CAN bus.
I tried to find a periodic signal on the CAN bus (the heartbeat), but I couldn't find anything that would qualify for much more than periodic noise. (only a couple of microvolts, really noisy, and extremely unreliable. However, it didn't seem to appear when I didn't have bdc-comm running or I didn't have my hand resting on my computer, if that makes any difference
)