Hi
I took a look at using the SO-8 wide footprint on the board but it is not so simple as the laout routes the signals 'through' the footprint pads. This makes it difficult to isolate the pads without interrupting signals that look to be required by the K20 debugger. Therefore it is probably best to add such a device to the connector pins.
Looking at the pins available I would chose the following connection (most pins close together on one connector) and use SPI1:
[VDD J9-4 / 0V J9-14]
SPI1_CS PTE-4 (J9-13)
SPI1_SCK PTE-2 (J9-9)
SPI1_MOSI PTE-1 (J2-20)
SPI1_MISO PTE-3 (J9-11)
Reset (J9-6)
Regards
Mark