You can enable IntelliSense for the Rhino SDK by performing the following steps.

1. Using Visual Studio, create a new "Utility" project and name it "RhinoSDK".
2. On the "Project" menu, select "Add to Project->Files..." and select all the header files for the Rhino SDK folder (C:\Program Files\Rhino 3.0 SDK\inc).
3. Save and close the project.
4. Open the plug-in project that you are working.
5. On the "Project" menu, select "Insert Project Into Workspace...". Select your new utility project.
6. Note, you may need to right click on your plug-in project, in either ClassView or FileView, to reset it as the active project.
7. You should now have intellisense for the Rhino SDK.
8. Repeat the above steps if you want IntelliSense enabled for OpenNURBS and RMAMfcUi headers.