The motor nameplate amperage is 6.6A, the NEC 460 wiring guidance for 3 phase is as follows:
Unless you have long distance between your VFD and motor (not recommended) then 14G (3 wire + ground) is fine. The VFD regulates it's output and will shut down if it exceeds it's programmed limits. Going from the VFD to your breaker box/outlet, 12G is rated to 20A (single phase), so would be OK for distances up to ~25', otherwise 10G. It is also recommended to fuse the VFD with a 30A cartridge or suitable breaker. Breakers are available with different overload characteristics, so either a C or D curve. Since the VFD's have soft starts, you have reduced inrush currents and less likely to trip the breaker. If you have a service disconnect switch before the VFD, a 25-30A rated switch should be fine.
Mike outlined the connection schematic for the PM-1340GT. The easiest build is to remove the existing control board, strip out the contacters and relay (just keep the 24VAC transformer for the light) and keep the barrier strips. Note the current control connections. Mount a single 4 pole relay to the board, and connect per the schematic. I can make up a diagrammatic picture/relay connections and parts list if needed. Just be aware that when a relay is mounted to a socket base, that the socket terminals are in a different location then the relay itself.
Also you need to decide if you want to use the current front panel switches or upgrade them. Regarding the VFD, you need to decide where you want to locate it, and if your going to use an electrical cabinet and adding a breaker/service disconnect.
This is a great VFD enclosure at a very reasonable price:
http://www.surpluscenter.com/Electr...s/LARGE-WHITE-ELECTRICAL-ENCLOSURE-1-4703.axd
You need to add a cooling fan, and some form of service disconnect. If you not familiar with mounting circuit breakers (I use DIN rail types), I would just use two 30A cartridge types in the enclosure (Like in Mike's enclosure). I recommend shielded wire between the VFD and the speed pot, and the VFD and the barrier strip. It is also recommended between the motor and the VFD, but not a deal breaker. The shields should be grounded at the VFD (not both ends), but you must run a separate ground wire to the motor. I use a single screw post in my VFD cabinet to tie all the grounds together.
Regarding programming the WJ200 VFD, I previously outlined some recommend parameters for this machine. This is a good starting point, I recommend programming in steps so you can figure out if you did something wrong.