I got it working. The problem was that I wasn't holding the ISP pin long enough on the reset.
Hi John,
It is good to hear you got it working.
Best Regards!
Carlos Mendoza
Technical Support Engineer
I have some additional information that may be useful.
For some reason I am able to access the UART command handle using a standard terminal and commands (See Table 27 Section 5.7 LPC18xx ARM Cortex-M3 microcontroller User's Guide) so I know I'm talking the the ISP command handler. For some reason the "?" synchronization handshake is not working and hence this is why mxli doesn't work. Interestingly enough I'm having the same issue with lpc1isp. There is a discussion in 5.4.4.1 that discussed this synchronization step but it appears I don't need this to access the ISP command handler.