The ChipWhisperer will eventually support programming this target. Until then, you will need an external programmer. This is connected via JTAG to the pin headers:
You can purchase clone JTAG programmers off AliExpress/E-Bay for low cost (search 'Xilinx JTAG').
NOTE: Schematic is marked as unapproved until hardware has been fully validated.
See GIT Repo for PDF of schematic.
See GIT Repo for gerber files.