It should be pretty easy, I wrote a little wizard that creates projects for use on the devkitPro toolchain (supports the DS among others) that could probably be modified for use with the official devkit. VS 10 is a bit more friendly with this sort of setup but it works on VS12 as well.
http://pern.drunkencoders.com/
The wizard is here and you will have to install it then open and edit the javascript files...no access to the official devkit so can't comment on how much of an undertaking this might be.
You may simply be able to edit the libnds template makefiles to point at the official toolchain and the wizard will just work as is (other than having to create a debug association).
There are also some good debugging tools if the toolchain that is based on gcc that will let you debug directly in visual studio with memory watches and custom viewers.