To install these plugins, point Eclipse at this site.
GMP GMF-NOTATION SDK 1.6.0RC4 S201206121200: contains runtime, source, and documentation.
GMP GMF-NOTATION SDK 1.5.0RC4 S201106071301: contains runtime, source, and documentation.
GMP GMF-RUNTIME SDK 1.6.1RC4 S201209131052: contains runtime, source, and documentation.
GMP GMF-RUNTIME SDK 1.5.0RC4 S201106071147: contains runtime, source, and documentation.
GMP GMF-TOOLING SDK 2.4.0M6 S201103301312: contains runtime, source, and documentation.