Analysis Services Load simulator (Free)

The sample code (Analysis Services Load Simulator aka ASLoadSim) contains a set of utilities used to generate a query load and test the scalability of Analysis Services server.

• ASQueryGenerator: console application to generate XML files with MDX queries to be used by the ASLoadSim library
• ASLoadSim: main library used by the Visual Studio for Testers to generate the MDX query load for Analysis Services server
• LoadTestReport: Reporting Services project to review the results of the simulation (logged to a SQL Server database)
• RssStyleSheet: auxilary file to be used by reporting services to define the report format

Make sure you read document "SSAS Load Testing Best Practices". 

More info here.

Also, please read installation guide by Christo Olivier here...