No way to be sure, but it certainly sounds like a standard ARM 20 pin jtag. Schematic for the LPC2148 board sparkfun sells is at
http://www.olimex.com/dev/images/lpc-p2148-sch.gif
3: TRST
5: TDI
7: TMS
9: TCK
11: RTCK
13: TDO
15: RST
I didn’t check your links yet to see if they match.
I take it your processor is BGA, or there is some other reason you can’t ohm from connector pin to IC pin?
You might want to post your processor type and any additional info you can scrape together, possibly in the ARM / LPC forum. It could be you have some pins in the wrong state at reset to enable jtag.