You use a rotary switch, usually 3 way maintained with two Normally Open Switch blocks. Center is STOP (both contacts open), turn one way for FORWARD, and the other way for REVERSE. Input GND connects to the input of both switches, FED connects to one switch block and REV to the other. Essentially the run command is when the switch is closed. You then need to program the VFD to tell it the source of the run command.
Pn 01 = 1
Pn 02 = 60 Hz
Pn 03 = 1 if you are setting the frequency from the panel with the pot (or 2 is using the buttons), if you have a mechanical Reeves drive then leave this at 60 Hz. If you have a pulley head, then get yourself an external speed pot 1, 2 or 5K and connect to the external potentiometer and set this parameter to 3.
Pn 04 = 2 this sets the source of the run commands to the inputs (i,e, FWD, REV, etc.)
Pn 05 =3
Pn 06 = 2
Pn 07 = 1
Pn 08 = 5 seconds acceleration
Pn 09 = 5 seconds deceleration
Pn 10 = 60 Hz Maximum motor freq. (can set this higher if needed, if a newer motor, something like 80)
Pn 11 = 15 Hz Minimum motor freq
Pn 12 = 60 Hz Assume this is the motor base frequency, i.e. the nameplate frequency.
Pn 13 = 0 (default)
Pn 14 = 80 Hz
The rest of the parameters I would leave the factory default. I am assuming you mill has a single speed 5 Hp motor, 4 pole, 1750 RPM at 60 Hz base speed.
A few other items. In general these type of VFD's overstate their output current, and their ability to run off of single phase which requires a more robust input section vs. a 3 phase input VFD. They often fail with high load starting, like compressors. Most people who consider buying these usually go to the next size up vs. the motor size they plan to run. There programming is very basic, and they run in what is known as V/Hz control of the motor without feedback. Most VFD's these days you need to put in the specific motor parameters and they run with feedback control, one method is called sensorlees vector control. These VFD's have a high failure rate, I have seen as high as 25%, but if they last a couple of weeks then chances are they will continue to work. The motor needle to be directly connected to the VFD terminals.
External speed pot
Switch, only use two NO switch blocks