As RJ stated:
Use the Pickit 3 programming utility not the MPlab program.
I used a PICkit 3 clone from Sure Electronics and their Universal ZIF socket. If that is what you have this is how you can program the Dongle chip:
I am assuming you have the PICkit 3 software installed.
First, download the “DONGLE2.HEX” firmware from the Wiki. Go to “Equipment Info” on the Wiki and click on the “Dongle” link. Click on the Dongle “Firmware” and save it somewhere on your computer where you can find it.
Put the chip in the 40-pin socket on the Universal ZIF socket. Make sure you have pin #1 on the chip at pin #1 on the socket.
Plug the socket into the PICkit 3 using the supplied wire.
Plug the PICkit 3 into the USB on your computer using the supplied wire.
Open the PICkit 3 software
Click on “Device Family” in the top menu. Choose PIC18.
In “Device Configuration, choose PIC18f2450 for the “Device”.
Click on “File” in the top menu. "Import" the “DONGLE2.HEX” file.
The Checksum will show “0A6F”.
Click on “Write”. It should write to the chip.
Once it is finished writing you can click on “Verify” to verify that the chip was written to.
The chip should be programmed.
I by no means am a pro at this. In fact, this is the first time I used a PICkit for anything. If someone sees a step I forgot or an easier way to do this please chime in.
There is a PICkit 3 on eBay with the correct size socket from “j1sys” that I have read is very easy to use and has documentation. The Sure Electronic clone did not come with any documentation. I had to fumble through it.