c139/c140 jtag anyone?

I'm at the point w/ flashing firmware where I feel like I need to use a debugger w/ JTAG. I figured I could probably use serial line logging somehow but JTAG seems better and I should learn it anyway. Has anyone pried open the shield on a c139/c140 and tried attaching to the JTAG test points that are just inside the shield next to the test points which are accessible via the battery compartment?