Hi,

Visual micro reads the Arduino build definitions which allow you to add new programmers.

The are stored in arduinoide\hardware\arduino\avr\[ver]

After adding a new programmer you can restart the ide or click "tools>visual micro>reload toolchains"

I'm not sure. There are a few things on google. "programmers.txt" and "arduino" and your programmer would be a good search

This one came up but might not be related

http://forum.arduino.cc/index.php?topic=264122.0

If you don't find a solution another user made use of some extended visual micro features which can be used to reference the "atprogram.exe" command tool of the atmel studio ide instead of avrdude from the arduino core. You don't need to use atmel but instead you can hard code the path to the atprogram.exe

The tool that programmers.txt reference are defined in platform.txt in the same folder.

You can find an example under programfiles\visual micro\arduino for vs\Micro Platforms\arduino16x\hardware\sam\programmers.atmel.txt

Visual micro will look for programmers.atmel.txt and programmers.vs.txt and programmers.txt, then append them to the programmers list so you can add your own. Obviously you would be adding to programfiles\visual micro\arduino for vs\Micro Platforms\arduino16x\hardware\avr\ if you have an avr board

Sorry it's not better documented. Tools>visual micro>verbose will let you see more easily what happens when you upload