There was an issue for our NuGet in TeamCity plugin support: TW-18927
As it turned out, it's possible to make NuGet use custom folder to store all packages. To do it you need to create NuGet.config file near your .sln file with the following content:
Starting from recent builds, NuGet plugin for TeamCity (versions 0.5.x and bundled) will be using this file to replace default packages location. The plugin uses repository.config file under packages folder to get the full list of projects that uses NuGet dependencies.
Download and Info:For more information, see NuGet plugin home page at:
NuGet support is included into TeamCity 7.0
or download a latest build from TeamCity here