IPMEMS distribution is a TAR.GZ archive or ZIP archive containing all the program files. Simple unpack it and type:
java -jar <ipmems-folder-path>/run-ipmems.sh
In Windows you can also run the ipmems.jar file but it will be dangerous because of ipmems.jar doesn't check the ipmems processes already running in your system. So, before any invocation of ipmems you must kill all the ipmems processes in the Windows Task Manager.
The Windows users can be interested in Professional or Enterprise versions of IPMEMS that have a tray icon, script editor and script debugging tools. These versions are distributed in both open-source and proprietary versions. You can get more information here.