The model compiler is a JAR file called modelcompiler.jar which can be found in <install-dir>\plugins\com.ibm.xtools.umldt.rt.core.tools_<version>\tools, where <version> is a version identifier that depends on the version of Model RealTime. The JAR file depends on a few other JAR files that are located in the subfolder called modelcompiler_lib.
If the Eclipse installation is read-only, the installation directory cannot be modified by the Model RealTime installer, and in that case the plugins with the model compiler are written to the writable Eclipse configuration folder. If the Eclipse installation is not read-only, the files will in addition be placed in <install-dir>\rsa_rt\tools from where it may be more convenient to access them.
It is recommended to use the same JVM for running the model compiler as is recommended to use for running Model RealTime.
Note: The model compiler needs to load some native libraries dynamically from the modelcompiler_lib folder mentioned above. This means that you need to have this path included in your PATH (on Windows) or LD_LIBRARY_PATH (on Linux) environment variable.