VR Studio

What you need

The only hardware you will need is an AVR ISP MKII programmer, the manufacturer part# is: ATAVRISP2. You can get it from DigiKey, Mouser or Farnell:

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/d972wmb_7f27p3nhb_b.jpg

And the software:

1. Download and install the AVRStudio 4.xx from here (you must register). This link was found here. During the installation process be sure to select the option "Install Jungo Drivers", this drivers are needed for the AVR programmer.
2. Download and install WINAVR from here, this will allow you program AVR devices in C++ (Is the real Arduino heart by the way), compile the PPM encoder source code and upload the code throught the AVR ISP programmer. . Always download the latest ".exe" version....
3. Power the board from your ESC or RC system as usual. You can plug it into any channel.
4. Connect the AVR programmer the APM Atmega 328 SPI port like this (you can either solder headers into the port on the board, or just put them in the AVR programmer's connector and hold them in the APM port):

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/IMG_4840.JPG

Automated procedure

Download the PPM Encoder zip file here. Unzip it to your desktop. If you are using 64-bit windows, you'll need to edit the batch file ("firmware_arduino_328_16mhz.bat") andchange the path to "Program Files (x86)". Like this: "C:\Program Files (x86)\Atmel\AVR Tools\STK500\Stk500.exe". If you're using regular 32-bit Windows, you can leave the batch file as it is.

Now click on the batch file. It should run in a DOS window. Press a key and you should get the following screen

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/batch.png

It should report a successful write, and you're done!