Given the testing of MP’s is crucial when you are implementing a new MP or you want to test your alerting following an MP review. I recommend you get your hands on MP Event Analyzer as this tool as is far superior to Event Create which is frustratingly limited in it’s functionality. Kevin Holman nicely articulates it’s usage.
One thing though is in order to use it .Net framework 4.0 is required on the host you run it on… In order to test any MP you will of course either have to break the application (Not really feasible in most circumstances) or simulate the errors so of course the MP Eventlog Analyzer will need to execute on the host to be tested. I have in the past handed finished packs to testing team with the exported test fire script so that the tests simply load the pack fire the script and hey presto alerts and functionality checked. This is more of a heads up really when liaising with test teams.
There is also a tool named NTEvent Log Explorer which can be used that will run on host machine but may have some limited functionality http://blogs.technet.com/b/momteam/archive/2008/04/02/eventlog-explorer.aspx