You will need a
VEX programming kit. It comes with EasyC for VEX. It is available from
www.vexlabs.com for $99.99.
EDIT: EasyC for VEX is significantly more limited than EasyC for FRC/Easyc Pro. This applies to EasyC Pro in Vex mode also.
If you really want to test the limits of EasyC for FRC applications then you really need to use a full size robot.
EDIT again: The VEX programming kit includes a USB>serial cable, VEX programmer(hardware), programmer>VEX cable, and EasyC.