I have trouble remembering this so I am going to blog this as a REMINDER !
To unseal a Management Pack you need to firstly get a PowerShell script which you can download from Boris's blog, there is an attachment MPtoXML.zip Copy the file into a location in your computer say C:\
Run the following as an example:
powershell C:\MpToXml.ps1 -mpFilePath:'d:\Microsoft.Exchange.Server.2003.Monitoring.mp' -outputDirectory:'d:\'
Thanks Boris for this wonderful script and blog entry.
I need to make sure I will not forget this AGAIN.