Sony1,
I am not aware of any JTAG procedure [yet]. I have read some discussions regarding it, but there is some confusion regarding whether the JTAG points are brought out to a board connection that can be utilized. One person did have a pix of the processor with circuit traces identified, but unless you can solder to a trace less than the width of a human hair, it wouldn't do any good.
I think one person had actually managed to desolder the entire processor from the board and reprogram it, but I doubt that any of us would have access to the equiment that they were using.
I am still watching for a JTAG procedure. Keep your eyes ad ears open.
RADAR