The initial release of the visual micro addin for visual studio is designed for arduino however it should be possible to use the system to program normal avr devices using visual studio. This is entirely untested but at the very leat this software will provide all the information and tools you need to adapt an avr solution.

Ignoring the arduino boards and library system you will find everything you need to adapt your own Visual Studio avr solution. AVR Intellisense, compliation, upload and much more