Hi,
maybe I’m totally wrong here, but what about supporting the NXP lpcxpresso board?
It costs about 20 Euros, comes with an USB-JTAG and! debug-wire interface and has a LPC1114 as target controller which can be separeted from the board to get a stand-alone JTAG interface.
But I`ve no idea, if we can get any information about USB access from NXP. It could be easier than Keil - they want to sell their chips and no software.