You can achieve import by providing a settings file with the /ResetSettings
argument.
devenv /ResetSettings c:\full\path\to\your\own.vssettings
This works from VS2005 onwards.
Although you can import from the command line, AFAIK there is no export functionality from the commandline. For that you could use a macro:
Sub ExportMacro()
DTE.ExecuteCommand("Tools.ImportandExportSettings", "/export:own.vssettings")
End Sub
Or from a commandline c# application (/reference EnvDte)
static void Main(string[] args)
{
var filename = "own.vssettings";
var dte = (EnvDTE.DTE) System.Runtime.InteropServices.Marshal.
GetActiveObject("VisualStudio.DTE"); // version neutral
dte.ExecuteCommand("Tools.ImportandExportSettings", "/export:" + filename);
}
To import the from the macro and/or c# program replace /export with /import